File watcher improvements

[tmat]

Ignore changes to files in output and intermediate output directories, unless they are listed in compiler inputs in the project file (e.g. source files generated to intermediate output directory by msbuild targets).

Ignore changes directories starting with ..

Postprocess changes to correct for misbehaving file system events and file writes using temporary intermediate files.

Add MAUI Blazor test.

Fixes #3282
Fixes #44912
Partially fixes #45183 (the content is not reloaded, but dotnet-watch does not crash).
Fixes #45011

[dotnet-policy-service]

Thanks for your PR, @tmat.
To learn about the PR process and branching schedule of this repo, please take a look at the SDK PR Guide.

[tmat]

@phil-allen-msft ptal

[phil-allen-msft]

I think Add then Delete is generally "nothing happened here". I think Delete then Add is equivalent to "Update". I'm thinking in particular about how something like the Resx code generator might work to product .Designer.cs from .resx, which could be Delete then Add. Does your change reflect DeleteThenAdd => Update? Or is that a not-hittable scenario?

[tmat]

Yup, delete+add translates to update. See https://github.com/dotnet/sdk/pull/45131/files#diff-703e093881ff7958e3d7a302b86e8a2c4c7b61825e6e8a379d743f93b6def1f3R17 for all cases.