refactor(generators): Migrate JavaScript generators to TypeScript (#7602)

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

* refactor(generators): Simplify getAdjusted

  Slightly simplify the implementation of getAdjusted, in part to
  make it more readable.  Also improve its JSDoc comment.

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

  The way the generator functions are added to
  javascriptGenerator.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 has been added to the to-do list in #7600.

* fix(generators): Fixes for PR #7602

* fix(generators): Fix syntax error

generators/javascript/variables.ts

@@ -0,0 +1,32 @@
+/**
+ * @license
+ * Copyright 2012 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * @fileoverview Generating JavaScript for variable blocks.
+ */
+
+// Former goog.module ID: Blockly.JavaScript.variables
+
+import type {Block} from '../../core/block.js';
+import type {JavascriptGenerator} from './javascript_generator.js';
+import {Order} from './javascript_generator.js';
+
+export function variables_get(
+  block: Block,
+  generator: JavascriptGenerator,
+): [string, Order] {
+  // Variable getter.
+  const code = generator.getVariableName(block.getFieldValue('VAR'));
+  return [code, Order.ATOMIC];
+}
+
+export function variables_set(block: Block, generator: JavascriptGenerator) {
+  // Variable setter.
+  const argument0 =
+    generator.valueToCode(block, 'VALUE', Order.ASSIGNMENT) || '0';
+  const varName = generator.getVariableName(block.getFieldValue('VAR'));
+  return varName + ' = ' + argument0 + ';\n';
+}