[Blazor] Investigate using fetch priority as an alternative for webassembly auto loading.

Instead of the max parallel downloads approach we use, we should investigate relying on fetch priority = low to let the browser handle the loading in the most efficient way possible.

The reason for the maxparallel downloads is that it delayed the signalr connection handshake which we didn't want to as the dlls won't be used until the next page load.

We can investigate making the signalr handshake use fetch priority high and let the other loads happen with low. That would still allow us to start interactivity as soon as possible and let the browser load things in the background more efficiently.