Clang coverage build fails for missing coverage data when testing coroutines with exception handling

[canepat]

Unit tests for code containing both coroutine calls activated by using asio::co_spawn and exception handling for such calls cause a problem in llvm-cov, which fails with

`Failed to load coverage: Malformed instrumentation profile data`

That's why unit tests for xxxRpcApi classes in commands package are missing or have been commented out.