refactor(generators): Migrate Python generators to TypeScript #7602 (#7617)

* refactor(generators): Migrate python_generator.js to TypeScript

* refactor(generators): Migrate generators/python/* to TypeScript

  First pass doing very mechanistic migration, not attempting to fix
  all the resulting type errors.

* fix(generators): Fix type errors in generator functions

  This consists almost entirely of adding casts, so the code output
  by tsc should be as similar as possible to the pre-migration .js
  source files.

* refactor(generators): Migrate generators/python.js to TypeScript

  The way the generator functions are added to
  pythonGenerator.forBlock has been modified so that incorrect
  generator function signatures will cause tsc to generate a type
  error.

* chore(generator): Format

  One block protected with // prettier-ignore to preserve careful
  comment formatting.

  Where there are repeated concatenations prettier has made a pretty
  mess of things, but the correct fix is probably to use template
  literals instead (rather than just locally disabling prettier).
  This is one of the items in the to-do list in #7600.

generators/python.ts

@@ -0,0 +1,53 @@
+/**
+ * @license
+ * Copyright 2021 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * @fileoverview Complete helper functions for generating Python for
+ *     blocks.  This is the entrypoint for python_compressed.js.
+ * @suppress {extraRequire}
+ */
+
+// Former goog.module ID: Blockly.Python.all
+
+import {PythonGenerator} from './python/python_generator.js';
+import * as colour from './python/colour.js';
+import * as lists from './python/lists.js';
+import * as logic from './python/logic.js';
+import * as loops from './python/loops.js';
+import * as math from './python/math.js';
+import * as procedures from './python/procedures.js';
+import * as text from './python/text.js';
+import * as variables from './python/variables.js';
+import * as variablesDynamic from './python/variables_dynamic.js';
+
+export * from './python/python_generator.js';
+
+/**
+ * Python code generator instance.
+ * @type {!PythonGenerator}
+ */
+export const pythonGenerator = new PythonGenerator();
+
+// Add reserved words.  This list should include all words mentioned
+// in RESERVED WORDS: comments in the imports above.
+pythonGenerator.addReservedWords('math,random,Number');
+
+// Install per-block-type generator functions:
+// Install per-block-type generator functions:
+const generators: typeof pythonGenerator.forBlock = {
+  ...colour,
+  ...lists,
+  ...logic,
+  ...loops,
+  ...math,
+  ...procedures,
+  ...text,
+  ...variables,
+  ...variablesDynamic,
+};
+for (const name in generators) {
+  pythonGenerator.forBlock[name] = generators[name];
+}