Add JSON with interpolation language support

Introduce a new 'json-interpolation' language that extends JSON with
${...} variable interpolation syntax. Features include:

- Monarch tokenizer with nextEmbedded for JavaScript inside ${...}
- Variable context API for custom completion and hover providers
- Diagnostics filtering to ignore errors inside interpolations
- Full JSON language service integration (formatting, symbols, etc.)
- Support for JSONC-style comments and trailing commas

Usage:
```typescript
monaco.languages.jsonInterpolation.jsonInterpolationDefaults.setVariableContext({
  getVariables: () => [
    { name: 'env', type: 'string', value: 'production' }
  ]
});
```

build/amd/vite.config.mjs

@@ -37,6 +37,10 @@ export default defineConfig(async (args) => {
 						__dirname,
 						'../../src/language/json/monaco.contribution.ts'
 					),
+					'language/json-interpolation/monaco.contribution': resolve(
+						__dirname,
+						'../../src/language/json-interpolation/monaco.contribution.ts'
+					),
 					'language/typescript/monaco.contribution': resolve(
 						__dirname,
 						'../../src/language/typescript/monaco.contribution.ts'