Remove macro registration hack (#499)

In old versions of IntelliJ platform it was only possible to register
macros of custom names. The only way to provide custom macro was to
override one of the existing macros. We've been overriding
`FileRelativePath` macro.

Unfortunately, since version 201.x of IntelliJ platform the hack does
not work, because the data structure to keep the macros has been
changed from a HashMap to a List. This means, the entries are not
overriden, but appended to the end of the list. MacroManager looks up
only for the first ocurrence of the name, so the one in the end of the
list will never be found if the name is not unique. The change was
done in this commit JetBrains/intellij-community@6183806

Luckily, the hack is not needed since
JetBrains/intellij-community@fdf6dbc.
This means, we can use any custom name for the macro

src/com/twitter/intellij/pants/macro/FilePathRelativeToBuiltRootMacro.java

@@ -3,7 +3,6 @@
 
 package com.twitter.intellij.pants.macro;
 
-import com.intellij.application.options.PathMacrosImpl;
 import com.intellij.ide.macro.Macro;
 import com.intellij.openapi.actionSystem.CommonDataKeys;
 import com.intellij.openapi.actionSystem.DataContext;
@@ -16,14 +15,11 @@
 
 public class FilePathRelativeToBuiltRootMacro extends Macro {
   /**
-   * Have to use one of the names listed in {@link PathMacrosImpl#ourToolsMacros} as a workaround due to
-   * https://intellij-support.jetbrains.com/hc/en-us/community/posts/206103709-Custom-macro
-   *
    * @return corresponding name of this macro
    */
   @Override
   public String getName() {
-    return "FileRelativePath";
+    return "PantsFilePathRelativeToBuiltRoot";
   }
 
   @Override

tests/com/twitter/intellij/pants/macro/FilePathRelativeToBuiltRootMacroTest.java

@@ -26,7 +26,7 @@ public void testFilePathRelativeMacro() throws Throwable {
     String expected = String.format("%s/testprojects/tests/java/%s.java", githubRepo, testClass.getQualifiedName().replace('.', '/'));
 
     VirtualFile fileSelected = testClass.getContainingFile().getVirtualFile();
-    String actual = MacroManager.getInstance().expandMacrosInString(githubRepo + "/$FileRelativePath$", false, getFakeContext(fileSelected));
+    String actual = MacroManager.getInstance().expandMacrosInString(githubRepo + "/$PantsFilePathRelativeToBuildRoot$", false, getFakeContext(fileSelected));
 
     assertEquals(expected, actual);
   }