[WIP] Trying to get Adaptive directions to work

[kellertuer]

This is for now just a first sketch from https://arxiv.org/abs/2409.00859

For now how to handle their Psi is not yet fully clear to me, it seems to stay very Eudliean.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 50 lines in your changes missing coverage. Please review.
✅ Project coverage is 99.50%. Comparing base (f493c01) to head (4bfbf44).

Files with missing lines	Patch %	Lines
src/plans/first_order_plan.jl	0.00%	50 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##            master     #561      +/-   ##
===========================================
- Coverage   100.00%   99.50%   -0.50%     
===========================================
  Files           91       91              
  Lines         9975    10025      +50     
===========================================
  Hits          9975     9975              
- Misses           0       50      +50     

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