ENH: add FaceArtifacts

[martinfleis]

Adding FaceArtifacts exposing the workflow from the upcoming paper by myself and @anastassiavybornova.

I still need to figure out how to test this since the method works for large metro areas but not for smaller samples. It needs the critical mass of elements. I will play with it if I find some useful samples.

[codecov]

Codecov Report

Merging #510 (943f490) into main (4f1176a) will increase coverage by 0.3%.
Report is 1 commits behind head on main.
The diff coverage is 96.8%.

@@           Coverage Diff           @@
##            main    #510     +/-   ##
=======================================
+ Coverage   97.2%   97.5%   +0.3%     
=======================================
  Files         24      24             
  Lines       4110    4176     +66     
=======================================
+ Hits        3996    4072     +76     
+ Misses       114     104     -10     

Files Changed	Coverage Δ
momepy/preprocessing.py	93.8% <94.7%> (+0.1%)	⬆️
momepy/tests/test_preprocess.py	100.0% <100.0%> (ø)

... and 5 files with indirect coverage changes

[martinfleis]

@anastassiavybornova can I ask for your review as well?

[jGaboardi]

Code seems sound, as far as I can tell. I will leave it up to @anastassiavybornova to review and approve.

[anastassiavybornova]

looks good to me!