Fix command "gdb-set" to handle long option --threadgroup and accept --longOption type words as just words for string types.
For example, MI command "17-gdb-set --thread-group i1 args --interpreter" is now acceptable, "--interpreter" was previous not valid.
Implementation of exec-run using lldb API.

Previously it was using run command which did not set the process
pointer in the sessionInfo. This commit also sends the proper
out-of-band data.