Implementation of backend plotting for slice_plot

[r3kste]

Summary of changes

1. Refactored slice_plot by separating data extraction logic from plotting code.
2. Added new parameters for range and share_axes, and vectorized labels in grid_plot.
3. Introduced MarkerData dataclass.

Plot Changes

Before	After

The only change is with the horizontal and vertical spacing.

Backend Comparision

Plotly	Matplotlib

PR Checklist

• Compared images before and after making changes
• Tests
• Documentation

[codecov]

Codecov Report

❌ Patch coverage is 97.14286% with 3 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/optimagic/deprecations.py	33.33%	2 Missing ⚠️
src/optimagic/visualization/slice_plot.py	98.59%	1 Missing ⚠️

Files with missing lines	Coverage Δ
src/optimagic/visualization/backends.py	99.02% <100.00%> (+0.23%)	⬆️
src/optimagic/visualization/convergence_plot.py	95.45% <ø> (ø)
src/optimagic/visualization/plotting_utilities.py	52.50% <100.00%> (-40.97%)	⬇️
src/optimagic/visualization/slice_plot.py	96.12% <98.59%> (+1.17%)	⬆️
src/optimagic/deprecations.py	98.17% <33.33%> (-0.91%)	⬇️

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[review-notebook-app]

Check out this pull request on 

See visual diffs & provide feedback on Jupyter Notebooks.

---

Powered by ReviewNB

[timmens]

Looks very good, thank you!! I only have a few minor comments, which I why I already approve.

Can you also check out the failures; although I think they are unrelated to your changes -- in that case; you can ignore them.