Recursive/global submodule commit

**Is your feature request related to a problem? Please describe.**
I have projects which use various submodules. When I make changes to the submodules of some projects, I see them as holistic but I have to go into each submodule and commit it with same message.

**Describe the solution you'd like**
It would be great if I could just type 'a' then 'c' then 'P' and have the repo and its submodules be recursively committed and pushed with the same commit message.