keybinding to copy commit message

**Is your feature request related to a problem? Please describe.**
copying commit message is hard; in Log tab, have to reword (r) then edit commit message (C-e) then copy according to editor.

**Describe the solution you'd like**

- add Keybinding to copy commit message
- option to copy only full body or commit brief message
- ability to copy multiple commit messages in order while commits are marked
- option to copy multiple commit message either full body or commit brief message

**Describe alternatives you've considered**
I'm using git-cliff to generate change log according to commit history.