Run ensemble experiment with design matrix

[xjules]

Issue Resolves https://github.com/equinor/ert/issues/8961

Approach This adds init_source to GenKwConfig, which if set to "design_matrix" the pd.DataFrame is expected as an argument to sample_prior. The function merge_with_existing_parameters in DesignMatrix is responsible to merge design matrix with existing parameters - in parameter_configuration. This requires to update storage version and thus create new storage snapshot.

TODO

• [ ] remove poly_design once reviewed.

(Screenshot of new behavior in GUI if applicable)

• [x] PR title captures the intent of the changes, and is fitting for release notes.
• [x] Added appropriate release note label
• [ ] Commit history is consistent and clean, in line with the contribution guidelines.
• [x] Make sure unit tests pass locally after every commit (git rebase -i main --exec 'pytest tests/ert/unit_tests -n logical -m "not integration_test"')

When applicable

• [ ] When there are user facing changes: Updated documentation
• [ ] New behavior or changes to existing untested code: Ensured that unit tests are added (See Ground Rules).
• [ ] Large PR: Prepare changes in small commits for more convenient review
• [ ] Bug fix: Add regression test for the bug
• [ ] Bug fix: Create Backport PR to latest release

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 88.70968% with 7 lines in your changes missing coverage. Please review.

Project coverage is 91.84%. Comparing base (d875982) to head (5b49260).

Files with missing lines	Patch %	Lines
...rc/ert/gui/simulation/ensemble_experiment_panel.py	28.57%	5 Missing :warning:
src/ert/config/design_matrix.py	92.30%	2 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8941      +/-   ##
==========================================
+ Coverage   91.64%   91.84%   +0.20%     
==========================================
  Files         433      433              
  Lines       26722    26761      +39     
==========================================
+ Hits        24489    24579      +90     
+ Misses       2233     2182      -51     

Flag	Coverage Δ
cli-tests	39.76% <79.03%> (+0.34%)	:arrow_up:
everest-models-test	34.66% <14.51%> (?)
gui-tests	72.14% <30.64%> (-0.07%)	:arrow_down:
integration-test	37.20% <14.51%> (-0.06%)	:arrow_down:
performance-tests	51.97% <30.64%> (-0.04%)	:arrow_down:
test	40.47% <14.51%> (-0.04%)	:arrow_down:
unit-tests	74.12% <77.41%> (+<0.01%)	:arrow_up:

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