Spin out rmw_gid_t and rmw_context_t from pub_sub_data into rmw_hazcat

[nightduck]

hazcat/hazcat/include/hazcat/types.h

Lines 134 to 135 in 21f2823

	rmw_gid_t gid; // gid of publisher
	rmw_context_t * context;

They should be placed with a generic data element that points at a struct in rmw_hazcat that holds rmw_git_t and rmw_context_t