fix(@angular/build): prevent stripping nested sourceMappingURL comments

[clydin]

When compiling files, the dev server and transformers strip original //# sourceMappingURL= comments. However, using a naive RegExp like /^\/\/# sourceMappingURL=[^\r\n]*/gm matches the comment even when it is embedded inside multiline template literals or string literals (such as inline web worker code), which causes template literals to become unterminated and fail compilation.

This introduces a robust, lexer-style utility removeSourceMappingURL that ignores occurrences of the comment when they appear inside single/double quotes, template literals, or block comments, preventing syntax errors in compiled chunks.

[gemini-code-assist]

Code Review

This pull request introduces a new utility function, removeSourceMappingURL, to safely strip top-level //# sourceMappingURL= comments from JavaScript code without affecting occurrences inside string literals, template literals, or block comments. This utility replaces several inline regex replacements across the codebase. The review feedback highlights a critical edge case where the proposed regular expression fails to handle nested template literals when a sourcemap comment is placed directly inside them without inner quotes. To address this, the reviewer suggests implementing a lightweight state-machine parser instead of a regular expression and provides corresponding unit tests to verify this behavior.