Update to net10.0 and packages to .NET 10

[davidwengier]

Fixes https://devdiv.visualstudio.com/DevDiv/_workitems/edit/2692923

[davidwengier]

Integration test failures is because we're using a v5.5 version of Roslyn, which has inserted into main, but Canary is still on a 5.4 version. Presumably will fix itself soon enough.

[davidwengier]

Test insertion: https://dev.azure.com/devdiv/DevDiv/_git/VS/pullrequest/704754

[ToddGrun]

Are the broken razor speedometer tests in the insertion going to be a problem?

---

In reply to: 3832634637

[davidwengier]

Are the broken razor speedometer tests in the insertion going to be a problem?

Yeah, turns out I misread or misremembered some PR titles in Roslyn, so consider this PR just a "prepare the changes for when everything else is ready to go in", not a "I'm going to merge this now". The speedometer tests, and local testing etc., are all due to the same thing: Razor tooling doesn't actually work at all with these changes yet :)