Remove use of custom isequal to compare scenarios

[gdalle]

DIT source

• Implement == between Scenarios
• Disallow passing custom isequal to check that scenarios have been preserved
• Replace it with scenario_intact=true/false

DIT extensions and tests

• Remove Flux- and Lux-specific isequal functions
• Deactivate tests of scenario intactness until I figure out why the scenarios change (Scenarios changing during Flux testing #488)

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 95.65217% with 1 line in your changes missing coverage. Please review.

Project coverage is 97.86%. Comparing base (f262504) to head (4ee3f4b).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...erentiationInterfaceTest/src/scenarios/scenario.jl	90.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #486      +/-   ##
==========================================
+ Coverage   97.83%   97.86%   +0.02%     
==========================================
  Files         106      107       +1     
  Lines        4305     4312       +7     
==========================================
+ Hits         4212     4220       +8     
+ Misses         93       92       -1     

Flag	Coverage Δ
DI	98.31% <ø> (+<0.01%)	⬆️
DIT	96.95% <95.65%> (+0.07%)	⬆️

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