Remove run context

[oyvindeide]

Simplify some of the logic around RunContext, and instead of passing for example iteration to RunContext, it is taken from Ensemble, which owns it. It also means passing the Ensemble directly to functions instead of going through the RunContext

(Screenshot of new behavior in GUI if applicable)

• [ ] PR title captures the intent of the changes, and is fitting for release notes.
• [ ] Added appropriate release note label
• [ ] Commit history is consistent and clean, in line with the contribution guidelines.
• [ ] Make sure tests pass locally (after every commit!)

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 96.29630% with 3 lines in your changes missing coverage. Please review.

Project coverage is 87.00%. Comparing base (f529971) to head (ef21d65).

Files	Patch %	Lines
src/ert/run_models/iterated_ensemble_smoother.py	85.71%	1 Missing :warning:
src/ert/run_models/multiple_data_assimilation.py	90.00%	1 Missing :warning:
src/ert/simulator/batch_simulator_context.py	90.90%	1 Missing :warning:

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #8271       +/-   ##
===========================================
+ Coverage   55.25%   87.00%   +31.75%     
===========================================
  Files         378      377        -1     
  Lines       23954    23918       -36     
  Branches      618      626        +8     
===========================================
+ Hits        13235    20810     +7575     
+ Misses      10638     3035     -7603     
+ Partials       81       73        -8     

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