Enable load results manually from any available iteration

[DanSava]

Issue
Resolves #8640

(Screenshot of new behavior in GUI if applicable)

Loading data

Checking plot results:

• 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 98.24561% with 2 lines in your changes missing coverage. Please review.

Project coverage is 90.74%. Comparing base (90d11ec) to head (af611f7).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...c/ert/gui/tools/load_results/load_results_panel.py	92.85%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8700      +/-   ##
==========================================
- Coverage   90.81%   90.74%   -0.07%     
==========================================
  Files         351      352       +1     
  Lines       21895    21926      +31     
==========================================
+ Hits        19884    19897      +13     
- Misses       2011     2029      +18     

Flag	Coverage Δ
cli-tests	39.22% <24.56%> (-0.03%)	⬇️
gui-tests	71.77% <92.10%> (+0.03%)	⬆️
performance-tests	49.35% <35.96%> (-0.02%)	⬇️
unit-tests	79.65% <56.14%> (-0.05%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[yngve-sk]

Sure we don't want a dropdown to enforce the selection of a valid iteration, rather than a text field (unless you want to be able to select multiple iterations etc?)

[DanSava]

Sure we don't want a dropdown to enforce the selection of a valid iteration, rather than a text field.

Sure we can convert it to a dropdown but that was not the focus of the parent issue. I can add an issue if you think a dropdown is more appropriate in this case.

(unless you want to be able to select multiple iterations etc?)

I am unsure it is possible to load data from multiple iterations into one ensemble.

[DanSava]

I created the issue #8819 to keep track of the dropdown conversion idea.

[oyvindeide]

Think we need to rethink a bit how we do this, so everything is kept in sync.

[DanSava]

Some tests are still needed for some of the new functionality but the implementation is ready for a review.

[oyvindeide]

Doing some testing, and looks good so far! It would be great if I also could see what <ITER> would be replaced by in the runpath (read only), adding a text field with for example:

f"<IENS> will be replace by: {ensemble.iteration}"

[oyvindeide]

Looks like a good improvement to me, a few minor questions

[oyvindeide]

LGTM!