Initial scaffolding for the rust bindings and tests

This is a small portion of GPLUGIN-133 to add rust bindings and test that we can load plugins written in rust. The rust portion of this is going to be done by a friend of mine, so to save them time we split it up so that I'm handling the build system side.

Testing Done:
ran with `meson -Drs=true` and verified it failed the unit tests as expected.

Bugs closed: GPLUGIN-136

Reviewed at https://reviews.imfreedom.org/r/628/