refactor(@angular/build): update private exports for additional usage

Add several additional APIs to the private export of the package.
Note that these are not considered part of the public API and
are intended for use only with the `@angular-devkit/build-angular` package.

(cherry picked from commit 1072ffc)

Author: clydin

packages/angular/build/src/private.ts

@@ -25,6 +25,10 @@ export { emitFilesToDisk } from './tools/esbuild/utils';
 export { transformSupportedBrowsersToTargets } from './tools/esbuild/utils';
 export { SassWorkerImplementation } from './tools/sass/sass-service';
 
+export { SourceFileCache } from './tools/esbuild/angular/source-file-cache';
+export { createJitResourceTransformer } from './tools/esbuild/angular/jit-resource-transformer';
+export { JavaScriptTransformer } from './tools/esbuild/javascript-transformer';
+
 // Utilities
 export * from './utils/bundle-calculator';
 export { checkPort } from './utils/check-port';