Add transform fault cookbook

[jdannberg]

Cookbook for making a transform fault and creating an initial condition for ASPECT.
This still has a WIP label because ideally we would wan to link to the corresponding ASPECT cookbook as well (which I haven't created yet).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (3c5e302) 93.55% compared to head (053f42e) 93.55%.
Report is 46 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #563   +/-   ##
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  Coverage   93.55%   93.55%           
=======================================
  Files          92       92           
  Lines        6343     6346    +3     
=======================================
+ Hits         5934     5937    +3     
  Misses        409      409           

see 2 files with indirect coverage changes

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[github-actions]

Benchmark	Main	Feature	Difference (99.9% CI)
Slab interpolation simple none	1.022 ± 0.006 (s=437)	1.021 ± 0.003 (s=447)	-0.2% .. +0.0%
Slab interpolation curved simple none	1.031 ± 0.006 (s=434)	1.031 ± 0.005 (s=441)	-0.1% .. +0.1%
Spherical slab interpolation simple none	1.264 ± 0.005 (s=349)	1.263 ± 0.005 (s=366)	-0.1% .. +0.1%
Slab interpolation simple curved CMS	1.098 ± 0.009 (s=406)	1.097 ± 0.007 (s=417)	-0.3% .. +0.1%
Spherical slab interpolation simple CMS	1.862 ± 0.006 (s=229)	1.858 ± 0.007 (s=257)	-0.3% .. -0.1%
Spherical fault interpolation simple none	1.269 ± 0.011 (s=334)	1.268 ± 0.004 (s=378)	-0.3% .. +0.1%
Cartesian min max surface	2.379 ± 0.017 (s=190)	2.377 ± 0.017 (s=191)	-0.3% .. +0.2%
Spherical min max surface	7.348 ± 0.017 (s=63)	7.346 ± 0.016 (s=62)	-0.1% .. +0.1%

[MFraters]

Looks great, thanks for writing this! The only comment I have is if you could split the lines a bit more, because now you have to scroll a lot to the side in the html documentation.

[jdannberg]

Thank you! I addressed your comments and also added a changelog entry.

I also made the corresponding ASPECT pull request, which can be found here: geodynamics/aspect#5575.

[jdannberg]

I fixed the changelog entry