Interactive Rebase: Edit commit

[Cyrillev91]

Hi,
During an interactive rebase, we use the edit keyword when we want to modify a commit.
The possible actions on this commit are:

• add a forgotten file (git add newfile.txt)
• modify a file (git add file.txt)
• delete a file (git restore --staged delfile.txt)
• modify the commit message.
  then continue the rebase.

Here with sourcegit when we launch a git rebase to edit a commit,:

The GUI does not allow us to see the actual content of the commit being edited (impossible to delete a file for example, not clear on the commit message of the rewritten one)

I think that for a better user experience:
We should display the commit marked with edit in the same way as when the amend button is checked in the case of the rewriting of the last commit:

• check the Amend box to clearly identify that we are rewriting a commit (It is not possible to do it manually because the checkbox is not displayed)
• in the stage: display the current files of the commit
• display the comment of the edited commit
• the commit button could be called "Ammend Commit" for clarity.
  So the user can modify the commit marked edit :
• add a forgotten file (with the sourcegit GUI)
• modify a file (with the sourcegit GUI)
• delete a file (with the sourcegit GUI)
• modify the commit message.
• Validate the changes of this commit by pressing the "Amend Commit" button
  (possibly add a new commit as suggested in To split a commit, Resolve of Interactive Rebase (Edit) needs a Commit button (besides Continue) #767).
  Then click on the continue button to continue the rebase.
  

Sample with the command line:
git rebase -i abcdef
pick commit x
edit commit y
pick commit z

git reset --soft HEAD^
git restore --staged path/to/unwanted_file (delete a file)
git add file (add/edit a file)
git commit -c ORIG_HEAD (for the same commit message)

git rebase --continue