refactor(generators): Restructure generator modules to contain side effects (#7173)

* refactor(generators): Move lang.js -> lang/lang_gernator.js

  Move the LangGenerator definitions into their respective
  subdirectories and add a _generator suffix to their filenames,
  i.e. generators/javascript.js  becomes
  generators/javascript/javascript_generator.js.

  This is to keep related code together and allow the `lang/all.js`
  entrypoints to be moved to the top level generators/ directory.

  No goog module IDs were changed, so playground and test code
  that accesses this modules by filename does not need to be modified.

* refactor(generators) Move lang/all.js -> lang.js

  - Move the entrypoints in generators/*/all.js to correspondingly-named
    files in generators/ instead—i.e., generators/javascript/all.js
    becomes generators/javascript.js.

  - Update build_tasks.js accordingly.

* fix(generators): Add missing exports for LuaGenerator, PhpGenerator

  These were inadvertently omitted from #7161 and #7162, respectively.

* refactor(generators): Make block generator modules side-effect free

  - Move declaration of <lang>Generator instance from
    generators/<lang>/<lang>_generator.js to generators/<lang>.js.
  - Move .addReservedWords() calls from generators/<lang>/*.js to
    generators/<lang>.js
  - Modify generators/<lang>/*.js to export block generator functions
    individually, rather than installing on <lang>Generator instance.
  - Modify generators/<lang>.js to import and install block generator
    functions on <lang>Generator instance.

* fix(tests): Fix tests broken by restructuring of generators

  Where these tests needed block generator functions preinstalled
  they should have been importing the Blockly.<Lang>.all module.

  Where they do not need the provided block generator functions
  they can now create their own empty <Lang>Generator instances.

* chore: Update renamings file

  - Fix a malformation in previous entries that was not detected by
    the renaming file validator test.
  - Add entries describing the work done in this and related recent
    PRs.

* fix: Correct minor errors in PR #7173

  - Fix a search-and-replace error in renamings.json5
  - Fix an incorrect-but-usable import in generator_test.js

scripts/gulpfiles/build_tasks.js

@@ -110,35 +110,35 @@ const chunks = [
   },
   {
     name: 'javascript',
-    entry: path.join(TSC_OUTPUT_DIR, 'generators', 'javascript', 'all.js'),
+    entry: path.join(TSC_OUTPUT_DIR, 'generators', 'javascript.js'),
     exports: 'module$build$src$generators$javascript',
     scriptExport: 'javascript',
     scriptNamedExports: {'Blockly.Javascript': 'javascriptGenerator'},
   },
   {
     name: 'python',
-    entry: path.join(TSC_OUTPUT_DIR, 'generators', 'python', 'all.js'),
+    entry: path.join(TSC_OUTPUT_DIR, 'generators', 'python.js'),
     exports: 'module$build$src$generators$python',
     scriptExport: 'python',
     scriptNamedExports: {'Blockly.Python': 'pythonGenerator'},
   },
   {
     name: 'php',
-    entry: path.join(TSC_OUTPUT_DIR, 'generators', 'php', 'all.js'),
+    entry: path.join(TSC_OUTPUT_DIR, 'generators', 'php.js'),
     exports: 'module$build$src$generators$php',
     scriptExport: 'php',
     scriptNamedExports: {'Blockly.PHP': 'phpGenerator'},
   },
   {
     name: 'lua',
-    entry: path.join(TSC_OUTPUT_DIR, 'generators', 'lua', 'all.js'),
+    entry: path.join(TSC_OUTPUT_DIR, 'generators', 'lua.js'),
     exports: 'module$build$src$generators$lua',
     scriptExport: 'lua',
     scriptNameExports: {'Blockly.Lua': 'luaGenerator'},
   },
   {
     name: 'dart',
-    entry: path.join(TSC_OUTPUT_DIR, 'generators', 'dart', 'all.js'),
+    entry: path.join(TSC_OUTPUT_DIR, 'generators', 'dart.js'),
     exports: 'module$build$src$generators$dart',
     scriptExport: 'dart',
     scriptNameExports: {'Blockly.Dart': 'dartGenerator'},