Update codespaces and devcontainer definitions to latest OSes

[ellahathaway]

Codespaces and dev container definitions should be updated to the latest OSes. A few examples of places where the OS needs to be updated:
 
https://github.com/dotnet/installer/blob/051677ef33279f1f0531f14d363c72ab0182abd2/.devcontainer/vmr-source-build/devcontainer.json#L6

https://github.com/dotnet/installer/blob/051677ef33279f1f0531f14d363c72ab0182abd2/src/SourceBuild/content/.devcontainer/devcontainer.json#L4

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.