[C][Java] Expand validation suites

- [x] Port existing tests to validation suite
- [x] Clean up C validation suite test helpers, see if they can't be structured better
- [ ] Make sure API is better covered
- [ ] Find some way to better cover error cases as well (e.g. failure of driver entrypoint function) - some of these tests may be specific to the driver manager
- [ ] Test things using the driver struct as well (tests should use both the driver manager and the library directly)