feat: add --watch-clear-screen option to clear terminal on rebuild

[krrish175-byte]

Closing issue

closes #4029

[Gedochao]

We'll need integration tests for this.
Spots to add them (for each sub-command supporting --watch):

• https://github.com/VirtusLab/scala-cli/blob/main/modules/integration/src/test/scala/scala/cli/integration/RunTestDefinitions.scala
• https://github.com/VirtusLab/scala-cli/blob/main/modules/integration/src/test/scala/scala/cli/integration/CompileTestDefinitions.scala
• https://github.com/VirtusLab/scala-cli/blob/main/modules/integration/src/test/scala/scala/cli/integration/PackageTestDefinitions.scala
• https://github.com/VirtusLab/scala-cli/blob/main/modules/integration/src/test/scala/scala/cli/integration/PublishLocalTestDefinitions.scala
• https://github.com/VirtusLab/scala-cli/blob/main/modules/integration/src/test/scala/scala/cli/integration/ReplTestDefinitions.scala
• https://github.com/VirtusLab/scala-cli/blob/main/modules/integration/src/test/scala/scala/cli/integration/TestTestDefinitions.scala

[Gedochao]

Thanks for contributing! I left some comments.
As noted above, we need tests for this.
Also, make sure to regenerate reference docs, since you're adding a new command line option. Refer to https://github.com/VirtusLab/scala-cli/blob/main/CONTRIBUTING.md#rules-for-a-well-formed-pr

[Gedochao]

Suggested change

	var isFirstRun = true
	val isFirstRun = new AtomicBoolean(true)

[krrish175-byte]

@Gedochao
Thanks, I implemented the requested changes: replaced isFirstRun vars with AtomicBoolean, added watchCls / watchClear aliases in SharedWatchOptions.scala, added integration tests for --watch-clear-screen (Run/Compile/Package/Test/Repl/Publish), and regenerated the reference docs. Ready for another review, anything else you'd like adjusted?

[Gedochao]

@krrish175-byte I'll try to take a look and review in the next couple of days, but I can already see it's failing formatting (need to run scalafmt; once again sending back to the contributing guide for all that stuff)

[Gedochao]

Currently:

• scalafix seems to be failing
• the newly added tests are failing on the CI as well