feature(blocks): Export block definitions (#5908)

* refactor: Provide a BlockDefinition type

* refactor: Split defineBlocksWithJsonArray

  Split defineBlocksWithJsonArray into:

  - createBlockDefinitionsFromJsonArray, which creates BlockDefinitions
    from a (possibly JSON-originated) POJsO array, having no side-effects
    except possibly issuing warnings to the console.
  - defineBlocks, which add any dictionary of BlockDefinitions to
    the Blocks dictionary.

* feat(blocks): Export block definitions per-module

  - Define all blocks in a local blocks dictionary, often using
    createBlockDefinitionFromJsonArray, without registering them.
  - Separately, use defineBlocks to register the exported
    BlockDefinitions at the end of each Blockly.blocks.*
    module.
  - In Blockly.blocks.all, create a blocks export that combines all
    of the blocks exports from the individual blocks modules.

* chore: have format script run clang-format on blocks/ too

scripts/gulpfiles/build_tasks.js

@@ -626,7 +626,7 @@ function cleanBuildDir(done) {
  * Runs clang format on all files in the core directory.
  */
 function format() {
-  return gulp.src(['core/**/*.js'], {base: '.'})
+  return gulp.src(['core/**/*.js', 'blocks/**/*.js'], {base: '.'})
       .pipe(clangFormatter.format('file', clangFormat))
       .pipe(gulp.dest('.'));
 };

scripts/gulpfiles/chunks.json

@@ -72,7 +72,6 @@
     "./core/menuitem.js",
     "./core/menu.js",
     "./core/contextmenu.js",
-    "./core/blocks.js",
     "./core/utils/global.js",
     "./core/utils/useragent.js",
     "./core/utils/svg.js",
@@ -264,6 +263,7 @@
     "./core/xml.js",
     "./core/connection.js",
     "./core/common.js",
+    "./core/blocks.js",
     "./closure/goog/base_minimal.js",
     "./core/blockly.js",
     "./blocks/variables_dynamic.js",