chore: add scalafix

[kpodsiad]

We have to agree on scalafix settings. Currently, they are very similar to the ones that can be found in Metals.

What I've found is that RemoveUnused have strange behavior - sometimes it removes only val name = and lefts right side of the assignment :/
Moreover, we have to be very careful, for example here

bloop/frontend/src/main/scala/bloop/Cli.scala

Lines 508 to 518 in 1b6633a

	val cancelCliClient = Task
	.deferFutureAction(cancel.asScala(_))
	.map { cancel =>
	if (cancel) {
	cliOptions.common.out.println(
	s"Client in $configDirectory triggered cancellation. Cancelling tasks..."
	)
	handle.cancel()
	}
	}
	.runAsync(ExecutionContext.ioScheduler)

there is a side effect (runAsync) that is assigned to the variable and we can't remove both sides. Probably the best way would be to iterate manually over those unused warnings.

scalafix can be run on frontend by frontend/scalafix

cc: @tgodzik

[tgodzik]

Looks sensible to me, did you try running scalafix? I remember I had some issues with it, but I tried fixing some dependencies causing those issues, so might be ok now.

[kpodsiad]

I temporarily removed RemoveUnused rule

[kpodsiad]

I think there's no point in adding scalafix to the CI for now - first we should handle initial sbt load overhead.

[tgodzik]

I think there's no point in adding scalafix to the CI for now - first we should handle initial sbt load overhead.

We can just add it to a separate job, no?

[kpodsiad]

I'll do rewrite generation of the test projects to not happen on sbt load task from Bloop next steps and then I'll add a CI job.

[tgodzik]

LGTM! Thanks for doing this!