fix(@angular/build): conditionally declare tslib in built library package

[alan-agius4]

Inspects Rolldown output chunk imports to detect whether any generated library bundle imports tslib (for example, when custom decorators or explicit resource management helpers are emitted). When tslib is imported and not already declared in the library's package.json dependencies, resolves the tslib version range from @angular/compiler (with fallback to tslib/package.json) and adds it to the emitted package.json.

Closes #34131

[gemini-code-assist]

Code Review

This pull request updates the library builder pipeline to automatically and conditionally inject tslib into the generated package.json dependencies when any output chunks import it, while preserving any user-defined tslib versions. It also ensures this dependency is correctly updated during watch mode when imports change. The feedback suggests a minor improvement to use a standard file path like package.json instead of a directory path with a trailing slash when initializing createRequire for better robustness.