rusticl/meson: enable rusticl unit testing

This enables the ability to run rust style unit tests in rusticl.

• !23778 (merged)
• This triggers a meson bug where the test module is not linked c++ stdlib, no link to the issue yet as it's new
• Triggers a meson bug where -I arguments of dependencies break it.
• Need to bump bindgen version to 0.60 to fix undefined behavior in generated tests.
• wait for mold 2.30.1 or newer.

https://github.com/mesonbuild/meson/pull/11902