run-make-support: add helpers for fs operations

[jieyouxu]

Noticed in #125683 (comment), we should add helpers for:

• fs operation wrappers that panic on failure and provide good context to aid debugging
  • e.g. wrap std::fs::remove_file(path) with run_make_support::fs::remove_file(path) but on panic shows the path we're trying to remove, so the test writer doesn't forget to check the result of fs operations.

cc @Oneirical in case you want to work on this.

UPDATE: we reworked rmake.rs tests to not run in the test sources directory so tmp_dir().join() is no longer relevant.

[jieyouxu]

Basically we want the support library to provide APIs almost like https://docs.rs/fs-err/latest/fs_err/ except panic-on-failure with good error messages instead of returning a Result.