[FR] move squash/fixup commits together with the parent in interactive rebase dialog

[kambala-decapitator]

Steps:

1. mark a commit as fixup or squash
2. move its parent

My expectation:
squash/fixup commit moves together with its parent as they're kinda "tied" together now

Actual:
only the parent moves

Screen.Recording.2025-08-15.at.23.19.49.mov

But not sure how feasible/sensible this FR is.