Rollup merge of #126862 - ChrisDenton:needs-symlink, r=jieyouxu

Add needs-symlink directive to compiletest

This is an alternative to #126846 that allows running symlink tests on Windows in CI but will ignore them locally if symlinks aren't available. A future improvement would be to check that the `needs-symlink` directive is used in rmake files that call `create_symlink` but this is just a quick PR to unblock Windows users who want to run tests locally without enabling symlinks.

Author: matthiaskrgr