Make sorting more logical in db editor

[PiispaH]

• Entity tree is now sorted by dimensionality, then by names.
• values in SearchBarEditor are now sorted logically so that 11 comes after 10.

Fixes #2869, #2319

Checklist before merging

• Unit tests have been added/updated accordingly
• Code has been formatted by black
• Unit tests pass

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.86%. Comparing base (c59fca2) to head (a794d6c).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2875      +/-   ##
==========================================
- Coverage   66.87%   66.86%   -0.01%     
==========================================
  Files         187      187              
  Lines       36384    36383       -1     
  Branches     6231     6232       +1     
==========================================
- Hits        24332    24328       -4     
- Misses      10753    10756       +3     
  Partials     1299     1299              

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