remove VersionDirectory from libraries

Before when building libraries, output files were placed inside a
directory named after the current version of the library, e.g.

    lib/build/UnoCore/1.2.3/

This is a relic from a time where it was possible to install multiple
versions of the same library side by side using Uno Package Manager.

Uno Package Manager was removed in favor of NPM in 2019, so we no longer
have this requirement and can remove the last directory part, e.g.

    lib/build/UnoCore/

We should still be able to load libraries built by older versions of
Uno using the version directory.

src/tool/engine/Packages/LibraryBuilder.cs

@@ -120,12 +120,7 @@ void Build(LibraryProject lib, PackageCache packageCache, List<LibraryProject> f
             }
             else if (Directory.Exists(lib.PackageDirectory))
             {
-                // Remove old versions
-                foreach (var dir in Directory.EnumerateDirectories(lib.PackageDirectory))
-                    if (dir != lib.VersionDirectory)
-                        Disk.DeleteDirectory(dir, true);
-
-                Disk.DeleteDirectory(Path.Combine(lib.CacheDirectory));
+                Disk.DeleteDirectory(lib.CacheDirectory);
             }
 
             var fail = TryGetFailedReference(lib, failed);
@@ -142,7 +137,7 @@ void Build(LibraryProject lib, PackageCache packageCache, List<LibraryProject> f
                     new BuildOptions
                     {
                         Configuration = GetConfiguration(lib),
-                        OutputDirectory = lib.VersionDirectory,
+                        OutputDirectory = lib.PackageDirectory,
                         PackageCache = packageCache,
                         Force = true
                     })

src/tool/engine/Packages/LibraryProject.cs

@@ -10,7 +10,6 @@ public class LibraryProject
     {
         public readonly Project Project;
         public readonly string PackageDirectory;
-        public readonly string VersionDirectory;
         public readonly string CacheDirectory;
         public readonly string ConfigFile;
         public readonly string PackageFile;
@@ -22,18 +21,16 @@ public LibraryProject(Project project, string sourceDir)
         {
             Project = project;
             PackageDirectory = Path.Combine(sourceDir, "build", project.Name);
-            VersionDirectory = Path.Combine(PackageDirectory, project.Version);
-            CacheDirectory = Path.Combine(VersionDirectory, ".uno");
+            CacheDirectory = Path.Combine(PackageDirectory, ".uno");
             ConfigFile = Path.Combine(CacheDirectory, "config");
             PackageFile = Path.Combine(CacheDirectory, "package");
         }
 
-        LibraryProject(LibraryProject lib, string versionDir)
+        LibraryProject(LibraryProject lib)
         {
             Project = lib.Project;
             PackageDirectory = lib.PackageDirectory;
-            VersionDirectory = versionDir;
-            CacheDirectory = Path.Combine(VersionDirectory, ".uno");
+            CacheDirectory = Path.Combine(PackageDirectory, ".uno");
             ConfigFile = Path.Combine(CacheDirectory, "config");
             PackageFile = Path.Combine(CacheDirectory, "package");
         }
@@ -44,11 +41,7 @@ public bool TryGetExistingBuild(out LibraryProject existing)
             if (!Directory.Exists(PackageDirectory))
                 return false;
 
-            var versions = Directory.EnumerateDirectories(PackageDirectory).ToArray();
-            if (versions.Length != 1)
-                return false;
-
-            existing = new LibraryProject(this, versions[0]);
+            existing = new LibraryProject(this);
             return true;
         }
 

src/tool/engine/Packages/PackageFile.cs

@@ -40,8 +40,11 @@ public static PackageFile Load(string dir)
         public readonly string RootDirectory;
         public string CacheDirectory => Path.Combine(RootDirectory, ".uno");
         public string Filename => GetName(RootDirectory);
-        public string Version => RootDirectory.GetPathComponent(-1);
-        public string Name => RootDirectory.GetPathComponent(-2);
+        public string Version => _version ?? RootDirectory.GetPathComponent(-1);
+        public string Name => _name ?? RootDirectory.GetPathComponent(-2);
+
+        readonly string _name;
+        readonly string _version;
 
         PackageFile(string dir)
         {
@@ -51,6 +54,8 @@ public static PackageFile Load(string dir)
         PackageFile(StuffObject stuff, string dir)
             : this(dir)
         {
+            stuff.TryGetValue(nameof(Name), out _name);
+            stuff.TryGetValue(nameof(Version), out _version);
             stuff.TryGetValue(nameof(BuildCondition), out BuildCondition);
             stuff.TryGetValue(nameof(SourceDirectory), out SourceDirectory);
             stuff.TryGetValue(nameof(IsTransitive), out IsTransitive);
@@ -74,6 +79,8 @@ public PackageFile(string installDir, string name, string version)
         public PackageFile(SourcePackage upk, string dir)
             : this(dir)
         {
+            _name = upk.Name;
+            _version = upk.Version;
             BuildCondition = upk.BuildCondition;
             IsTransitive = upk.IsTransitive;
 
@@ -95,6 +102,8 @@ public PackageFile(SourcePackage upk, string dir)
         public void Save()
         {
             new StuffObject {
+                {nameof(Name), Name},
+                {nameof(Version), Version},
                 {nameof(BuildCondition), BuildCondition},
                 {nameof(SourceDirectory), SourceDirectory},
                 {nameof(IsTransitive), IsTransitive},

src/tool/engine/Packages/PackageSearchPaths.cs

@@ -27,10 +27,14 @@ public IEnumerable<DirectoryInfo> EnumeratePackageDirectories(string name = "*")
         public IEnumerable<DirectoryInfo> EnumerateVersionDirectories(string name = "*", string version = null)
         {
             version = version ?? "*";
-            foreach (var package in EnumeratePackageDirectories(name))
-                foreach (var dir in package.EnumerateDirectories(version))
-                    if (PackageFile.Exists(dir.FullName))
-                        yield return dir;
+            foreach (var package in EnumeratePackageDirectories(name)) {
+                if (PackageFile.Exists(package.FullName))
+                    yield return package;
+                else
+                    foreach (var dir in package.EnumerateDirectories(version))
+                        if (PackageFile.Exists(dir.FullName))
+                            yield return dir;
+            }
         }
 
         public DirectoryInfo[] GetOrderedVersionDirectories(string name = "*", string version = null)