tests: Build tests into separate executables

Allow selectively run single test cases and produce useful reports on
the pass/fail ratio.
doc: Fix doxydoc build
tests: Remove garbage - empty source files
fixup: Added functionality to track bluetooth state changes

This fixes typo in 4d1d436 (Added functionality to track bluetooth state
changes)

[buteo-syncfw] Fix bluetooth state changes tracking
tests: Update tests
SyncProfile: add TODO for API cleanup