Include hash of Blazor WASM assemblies in URLs

[mkArtakMSFT]

[SteveSandersonMS]

I don't think there's anything else for us to do here. We now have the content hashes in the blazor.boot.json file (and service worker asset manifest for PWAs), and the .js code already takes care of requesting them with cache: no-cache when they are not already cached locally.

@javiercn Please comment if you think something else is still needed here, but I'll close now because I think this is now handled.