Fix changing slider path segment type not being undoable

[B3nn1]

Fixes #26328.

Unfortunately, this creates a new issue where selecting a HitObject that is the first in a new combo can create another, seemingly redundant saveState (I believe due to TernaryState changes from the MenuItem.)
This is possibly related to #10314.
Hence why I decided to post this as a draft for now.

[OliBomby]

I can't recreate the issue you described. I debugged it with a breakpoint in the action and it never triggered when i selected a bunch of hitobjects. From looking at the code it also seems that only clicking the menu item should be able to trigger the action.

[B3nn1]

I can't recreate the issue you described.

Unfortunately, I can consistently recreate it with a setup like shown in the video. I tried to but couldn't figure out why LegacyBeatmapEncoder generates a different encode output after just selecting something else and not changing anything in the map itself.

2024-01-24.11-27-30_edit.mp4

[OliBomby]

This time I was able to recreate the issue and I looked further into it. The issue seems to be unrelated to your changes and instead related to #11901. Your issue setup also works on the current master branch.

So I think your changes are good to go.