o/i/apparmorprompting/common: add prompting path patterns

[olivercalder]

This PR splits out the path pattern matching, expansion, and precedence from the previous PR to add the common package in its entirety: #13668

The path pattern-related work there itself is largely a port of a previous PR against the prompting branch: https://github.com/olivercalder/snapd/pull/30

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 78.93%. Comparing base (2b48274) to head (da0e748).

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Additional details and impacted files

@@            Coverage Diff             @@
##           master   #13730      +/-   ##
==========================================
+ Coverage   78.91%   78.93%   +0.02%     
==========================================
  Files        1043     1044       +1     
  Lines      134345   134537     +192     
==========================================
+ Hits       106014   106203     +189     
- Misses      21719    21720       +1     
- Partials     6612     6614       +2     

Flag	Coverage Δ
unittests	78.93% <100.00%> (+0.02%)	:arrow_up:

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[zyga]

I've started to review this now

[olivercalder]

This should be moved to the interfaces/prompting package, related to #13849 and #13850.