Allow stage/revertSelectedRanges keybinding not just in diffEditor

[NicoWeio]

#93706 introduced default keybindings for stageSelectedRanges, unstageSelectedRanges and revertSelectedRanges as per issue #93564, but they don't work in the regular editor, while running the command from the command palette gives the intended result.
Therefore, I propose to extend the when clauses of stageSelectedRanges and revertSelectedRanges. unstageSelectedRanges remains unchanged, since it seems to have no effect in a regular editor.

Note: I tried to be as conservative and left isInDiffEditor intact, but that's probably not needed.

[NicoWeio]

I just noticed one should also be able to invoke stageSelectedRanges / revertSelectedRanges on the current line without selecting the line. Fixed in 324a6a2.

At this point, one could even consider using editorFocus, but I'm not sure. 🤷🏼‍♂️