Move linting to a separate GitHub Actions workflow

[Snuffleupagus]

This way we introduce more parallelism in the GitHub Actions tests, which should reduce overall runtime and thus cannot hurt.

[timvandermeij]

Thank you for doing this; it's in line with the plan I also had to move every target into its own workflow because it increases parallelism and makes it easier to spot what failed without having to go through logs.

[Snuffleupagus]

Thank you for doing this; it's in line with the plan I also had to move every target into its own workflow because it increases parallelism and makes it easier to spot what failed without having to go through logs.

Agreed, nice that we've been thinking the same thing here :-)

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@calixteman Can you please mark the new "Lint" workflow as Required, so that we cannot accidentally land something that fails linting?