Replace Transient state for Starting and Halting

[ben-grande]

Draft as untested.

For: QubesOS/qubes-issues#10966
Requires: QubesOS/qubes-core-admin-client#480

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.66%. Comparing base (b2fea1d) to head (133b4c6).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #455      +/-   ##
==========================================
- Coverage   69.71%   69.66%   -0.05%     
==========================================
  Files          17       17              
  Lines        4029     4029              
==========================================
- Hits         2809     2807       -2     
- Misses       1220     1222       +2     

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[ben-grande]

Without this PR, the application crashes when it sees a power state it is not aware of, such as Starting. This PR fixes it, but for next time, each client application should handle unknown states gracefully.

Jul 16 17:06:21 dom0 python3[186072]: Traceback (most recent call last):
                                        File "/usr/lib/python3.13/site-packages/qubesmanager/qube_manager.py", line 173, in paint
                                          self.stateIcons[index.data()['power']].pixmap(iconSize))
                                          ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^
                                      KeyError: 'Starting'
Jul 16 17:06:21 dom0 systemd-coredump[187813]: [] Process 186072 (qubes-qube-mana) of user 1000 dumped core.

Is a transition period necessary? Where the server sends Transient in place of Starting?