Move statistics customization to sidebar

[MagnusSletten]

Issue
Resolves #14030

Currently blocked by #14025 since it's based on some changes within that PR.

Approach

Added a collapsible statistics customization pane to the sidebar. The functionality remains the same, with one important change: the settings are no longer defined per key. Switching between keys therefore preserves the selected statistics styling.

• 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 unit tests pass locally after every commit (git rebase -i main --exec 'just rapid-tests')

When applicable

• When screenshots are changed: Review screenshot-PR in ert-testdata,
  merge screenshot-PR in ert-testdata before merging this PR.
• 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: Add backport label to latest release (format: 'backport release-branch-name')

[ertomatic]

Screenshots differ from baselines. A baseline update PR has been prepared: equinor/ert-testdata#65

[codecov-commenter]

Codecov Report

❌ Patch coverage is 98.27089% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.50%. Comparing base (77e0dbb) to head (0f65ad9).

Files with missing lines	Patch %	Lines
...otting/widgets/plot_controls/statistics_options.py	98.05%	3 Missing ⚠️
...ui/plotting/widgets/plot_controls/style_options.py	96.51%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #14031      +/-   ##
==========================================
+ Coverage   91.48%   91.50%   +0.01%     
==========================================
  Files         487      488       +1     
  Lines       34086    34275     +189     
==========================================
+ Hits        31184    31363     +179     
- Misses       2902     2912      +10     

Flag	Coverage Δ
cli-tests	35.90% <0.00%> (-0.20%)	⬇️
fuzz	43.48% <19.02%> (-0.18%)	⬇️
gui-tests	58.80% <91.93%> (+0.14%)	⬆️
performance-and-unit-tests	80.08% <98.27%> (+0.05%)	⬆️
test	45.78% <19.02%> (-0.19%)	⬇️

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

Files with missing lines	Coverage Δ
...ting/customization_dialog/customize_plot_dialog.py	79.54% <ø> (-1.52%)	⬇️
...gui/plotting/customization_dialog/style_chooser.py	88.43% <100.00%> (-6.61%)	⬇️
src/ert/gui/plotting/ert_plots/statistics.py	91.34% <100.00%> (ø)
src/ert/gui/plotting/plot_window.py	80.04% <100.00%> (+0.67%)	⬆️
...ert/gui/plotting/widgets/plot_controls/__init__.py	100.00% <100.00%> (ø)
...t/gui/plotting/widgets/plot_controls/style_edit.py	100.00% <100.00%> (ø)
src/ert/gui/plotting/widgets/plot_widget.py	88.38% <100.00%> (-0.64%)	⬇️
...otting/widgets/plot_controls/statistics_options.py	98.05% <98.05%> (ø)
...ui/plotting/widgets/plot_controls/style_options.py	96.51% <96.51%> (ø)

... and 3 files with indirect coverage changes

[codspeed-hq]

Merging this PR will not alter performance

✅ 36 untouched benchmarks

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_{Comparing MagnusSletten:move-statistics (0f65ad9) with main (77e0dbb)}

[MagnusSletten]

Closed due to the decision to move away from even more legacy code.