This adds a fixer for MVVMTK0034, that simply swaps the field reference for what will be generated for the property. It leaves the qualification intact, basically just doing a text swap. Because it's very a very simple fixer, the built-in batch fixall provider works just fine and does not need special handling.
While I implemented the fixer and added some tests, I did not actually set up all the msbuild goop for properly packaging this as part of the existing packages (as, frankly, the multi-targeting and msbuild setup in this repo is very complicated and I didn't feel like trying to grok exactly how to add it given the setup). The fixer assembly needs to be put next to the analyzer assemblies. This PR will be editable by maintainers, so feel free to implement this in-place in the PR itself.
Fixes https://github.com/CommunityToolkit/dotnet/issues/577.
Sergio Pedri