Make managed debugging on Linux possible (attach, load, bp, exceptions, stacktrace)

Make managed debugging on Linux possible (attach, load, bp, exceptions, stacktrace)

Fixes that were required to achieve that
1. Funnel SIGTRAP into EE debugger.
2. Making that memory allocated by EE debugger is executable.
3. Disable metadata reading optimizations which are not working on Linux.
4. Workaround RtlRestoreContext not properly working with EFlags.
5. Avoid calls to ShimRemoteDataTarget.GetContext on Linux, it is not
implemented and not needed for pure managed debugging.
6. Adjust IP value after breakpoint SIGTRAP to meet debuggers expectations.