1. Added a new common completion TypeCategoryNames to provide a list of category names for completion;
2. Applied the completion to these commands: type category delete/enable/disable/list/define;
3. Added a related test case;
4. Bound the completion to the arguments of the type 'eArgTypeName'.
Reviewed By: teemperor, JDevlieghere
Differential Revision: https://reviews.llvm.org/D84124