break: move shorebird_code_push_io and _web into src/

Users were sometimes importing the _web version thinking it
was the "web safe" import, rather than shorebird_code_push.dart
and then being surprised when ShorebirdCodePush did nothing.

Fixes shorebirdtech/shorebird#1209

shorebird_code_push/CHANGELOG.md

@@ -1,3 +1,9 @@
+# 1.2.0
+- break: `package:shorebird_code_push/shorebird_code_push_io.dart` and
+  `package:shorebird_code_push/shorebird_code_push_web.dart` have moved into
+  `src/` to discourage accidental direct import of these files.  Please import
+  `package:shorebird_code_push/shorebird_code_push.dart` instead.
+
 # 1.1.0
 
 - feat: introduce `isShorebirdAvailable` to determine whether the Shorebird Engine is detected

shorebird_code_push/lib/shorebird_code_push.dart

@@ -1,5 +1,5 @@
 /// Get info about your Shorebird code push app
 library shorebird_code_push;
 
-export 'shorebird_code_push_io.dart'
-    if (dart.library.html) 'shorebird_code_push_web.dart';
+export 'src/shorebird_code_push_io.dart'
+    if (dart.library.html) 'src/shorebird_code_push_web.dart';

shorebird_code_push/lib/shorebird_code_push_io.dart → shorebird_code_push/lib/src/shorebird_code_push_io.dart

@@ -4,6 +4,9 @@ import 'package:shorebird_code_push/src/shorebird_code_push_ffi.dart';
 import 'package:shorebird_code_push/src/shorebird_code_push_noop.dart';
 import 'package:shorebird_code_push/src/updater.dart';
 
+/// Applications should not import this file directly, but
+/// import `package:shorebird_code_push/shorebird_code_push.dart` instead.
+
 /// {@template shorebird_code_push}
 /// Get info about your Shorebird code push app.
 /// {@endtemplate}

shorebird_code_push/lib/shorebird_code_push_web.dart → shorebird_code_push/lib/src/shorebird_code_push_web.dart

@@ -1,6 +1,9 @@
 import 'package:shorebird_code_push/src/shorebird_code_push_base.dart';
 import 'package:shorebird_code_push/src/shorebird_code_push_noop.dart';
 
+/// Applications should not import this file directly, but
+/// import `package:shorebird_code_push/shorebird_code_push.dart` instead.
+
 /// {@template shorebird_code_push}
 /// Get info about your Shorebird code push app.
 /// {@endtemplate}

shorebird_code_push/test/shorebird_code_push_io_test.dart

@@ -1,7 +1,7 @@
 import 'dart:async';
 
 import 'package:mocktail/mocktail.dart';
-import 'package:shorebird_code_push/shorebird_code_push_io.dart';
+import 'package:shorebird_code_push/src/shorebird_code_push_io.dart';
 import 'package:shorebird_code_push/src/updater.dart';
 import 'package:test/test.dart';