Update Blazor WASM web.config

[guardrex]

Fixes #20205

Thanks @cornem! 🎷 and @glararan! 🚀

• AFAICT, no need to version the updates. This should work with 3.x and 5.x.
• Decided in the DRAFT here NOT to serve double-compressed assets (in spite of the framework producing them), which I think would have unpredictable (and often not good) results. If a dev wants to change the file for things like PNG, WOFF, etc., they can do so on their own. The pattern here is easy to follow.
• For static and dynamic compression, I go off of what's in a typical (default) applicationHost.config. These removals look like the only ones that we need here.
• No need to remove and then add back existing MIME maps in the typical (default) scenario, so I take those out.
• Per Ben's original file, I retain the MIME change for DLLs. He goes from application/x-msdownload to application/octet-stream, so let me know if that needs to be addressed (i.e., dropped). 👂