[FLTMGR]
- Partially implement registering contexts
- Add a misc file which contains stubs of the APIs needed in the test suite
- Export some APIs needed by the test suite
[KMTESTS]
- Create a File System Mini-filter wrapper to host drivers for the filter manager tests
- Add a test file which will be used for testing that mini-filters load correctly
- Add a test file which will be used to write tests for IRP_MJ_CREATE requests
