feat request: adding in checks for files in the staging area automatically

[wayne-wang-1119]

The current behavior is files need to be added to the staging area first before generating commit message, is it possible to add:

When trying to generate a commit message, if staged changes is empty, use all the changed and automatically push all the changes to the staged changes and generate commit message?

[Sitoi]

This is a good idea, but it is very likely that there will be too many documents exceeding the token length.

[bramburn]

one option is to just iterate slowly on EACH file which would be costly . maybe have this as an option?