Include OSPlugin functions in `find_functions` output

[JSCU-CNI]

This PR fixes a (slightly different) regression of https://github.com/fox-it/dissect.target/issues/421.

Since the plugin internals refactor #889 only __regular__ plugins are returned when invoking find_functions (-> _generate_long_paths). Previously OSPlugin specific functions were also returned.

See the added test for steps how to reproduce using target-query -l "*" <target>.

[codecov[bot]]

Codecov Report

:x: Patch coverage is 88.37209% with 5 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 80.70%. Comparing base (4ae4dbc) to head (f648a70). :warning: Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
dissect/target/tools/utils.py	66.66%	3 Missing :warning:
dissect/target/plugin.py	94.11%	2 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1135      +/-   ##
==========================================
- Coverage   80.70%   80.70%   -0.01%     
==========================================
  Files         374      374              
  Lines       33288    33286       -2     
==========================================
- Hits        26865    26863       -2     
  Misses       6423     6423              

Flag	Coverage Δ
unittests	80.70% <88.37%> (-0.01%)	:arrow_down:

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[JSCU-CNI]

Seems like something here is not deterministic. Sometimes the path of the selected plugin is "os.unix._os.users" and sometimes it is "os.unix.linux._os.users"

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #1135 will not alter performance

_{Comparing JSCU-CNI:fix/os-functions-filter-tree-match (f648a70) with main (4ae4dbc)}

Summary

✅ 8 untouched benchmarks

[JSCU-CNI]

Is there anything we can do to move this PR forward?

[JSCU-CNI]

It seems part of this PR was implemented by @Miauwkeru in https://github.com/fox-it/dissect.target/commit/fb96bdd4886bd8f7828feb67321ef23f00ef387b.

[Schamper]

@JSCU-CNI I've made some changes, let me know if this works in line with how you would expect this to work. I've made it so that wildcarding will only pick up "OS functions" from the target's own OS (and superclasses). This also works reliably on DefaultOSPlugin now.

I also changed some tests around, removing the atrocious mock data that was there before with something more realistic (and way easier to debug and wrap your head around).

[JSCU-CNI]

Completely missed this, thanks for the commit @Schamper. At a first glance this seems to achieve exactly what we want.