Fix #21242: Add REPL flag to quit after evaluating init script

[noti0na1]

Fix the remaining part of #21242

Evaluate the init script and skip the interactive mode in REPL.

Test with flag at REPL startup:

> ./bin/scalaQ --repl-init-script 'println("Hello from init script!"); val i = 2 * 2' --repl-eval
[warning] MainGenericRunner class is deprecated since Scala 3.5.0, and Scala CLI features will not work.
[warning] Please be sure to update to the Scala CLI launcher to use the new features.
[warning] Check the Scala 3.5.0 release notes to troubleshoot your installation.
Hello from init script!
val i: Int = 4
>

[Gedochao]

Can we have a test case for this?
Just to verify the output, and that a sub-terminal doesn't get created.
Preferably with dotty.tools.repl.Main, rather than the legacy runner.

[noti0na1]

Can we have a test case for this?

You can test it locally, the process terminates immediately, but I don't know how to create a test to verify that.

[Gedochao]

You can test it locally, the process terminates immediately, but I don't know how to create a test to verify that.

I can see that it works the way it is now, but an automated anti-regression test would go a long way.
I believe it'd be sufficient to call the REPL main method with the --repl-init-script and --repl-eval args, and then verify the output on stdout.

[noti0na1]

Oh, I find this test we may be able to reuse: compiler/test/dotty/tools/scripting/BashExitCodeTests.scala