Introduce LocalVM to extract BaseVM being smaller class

[fepitre]

It prepares the work for RemoteVM.

[fepitre]

@marmarek can you run openQA on it please?

[marmarek]

Sure, I can, but I think you may want to first take care of unit tests, this one looks like a real issue:

  File "/home/user/builds/QubesOS/qubes-core-admin/qubes/vm/__init__.py", line 403, in load_extras
    for parent in self.xml.xpath("./devices"):
                  ^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'xpath'

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.53%. Comparing base (039b7d3) to head (e308e84).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #637      +/-   ##
==========================================
+ Coverage   69.49%   69.53%   +0.03%     
==========================================
  Files          58       58              
  Lines       12465    12478      +13     
==========================================
+ Hits         8663     8676      +13     
  Misses       3802     3802              

Flag	Coverage Δ
unittests	69.53% <100.00%> (+0.03%)	⬆️

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[fepitre]

Sure, I can, but I think you may want to first take care of unit tests, this one looks like a real issue:

  File "/home/user/builds/QubesOS/qubes-core-admin/qubes/vm/__init__.py", line 403, in load_extras
    for parent in self.xml.xpath("./devices"):
                  ^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'xpath'

Fixed.