Auto merge of #96493 - chbaker0:issue-96342-fix, r=Mark-Simulacrum

Auto merge of #96493 - chbaker0:issue-96342-fix, r=Mark-Simulacrum

Add compiletest and bootstrap "--skip" option forwarded to libtest

With this PR,  "x.py test --skip SKIP ..." will run the specified test suite, but forward "--skip SKIP" to the test tool. libtest already supports this option. The PR also adds it to compiletest which itself just forwards it to libtest.

Adds the functionality requested in https://github.com/rust-lang/rust/issues/96342. This is useful to work around tests broken upstream.

https://github.com/rust-lang/rust/issues/96362#issuecomment-1108609893 is the specific test issue my project is trying to work around.