Apply patch: "Add {un,re}do actions to edit menu" by Guillermo Martinez

https://mail.kde.org/pipermail/umbrello-devel/2022-April/023235.html

This patch adds support to use of standard location and shortcuts
for {un,re}do actions.

umbrello/uml.cpp (UMLApp::initActions)
- Use `KStandardAction::{un,re}do' to create {un,re}do actions, adding
  a tooltip to describe them.