Stem length change is not undoable

Steps to reproduce:
1) Create a score, put there two notes, the first one should have a stem.
2) Double-click the first note's stem, drag a grip point to change its length
3) Undo
Expected results: stem length returns to its original size
Actual results: stem retains its changed size, the second note is removed.

#32576: Undo change beam property of first note of beamed group doesn't reset stem length might be related to this issue.

Tested on
OS: Debian GNU/Linux 9 (stretch), Arch.: x86_64, MuseScore version (64-bit): 3.0.0, revision: bbd9220