Refactor some functions in histogram tools

[jo-mueller]

@zoccoler small refactoring changes to #390. I changed the baplotter dependency to the branch on the repo to make sure that tests can pass, will change it as soon as 0.3.1 is released.

PS: I tested the functionality manually and everything seems to work. Tests are passing locally.

Long copilot description

This pull request refactors the color management logic in the napari_clusters_plotter widget to improve clarity and maintainability. Key changes include replacing redundant methods, simplifying color application, and introducing a new utility function for layer color updates.

Refactoring and Simplification:

• Replaced the _on_show_plot_overlay method with a direct connection to _update_layer_colors, removing unnecessary indirection in handling the show_color_overlay_signal. [1] [2]
• Simplified the _update_layer_colors method by consolidating logic for applying default and indexed colors, and removing redundant code paths.

Utility Function Addition:

• Introduced a new _apply_layer_color utility function to centralize the logic for applying colors to layers, improving code reuse and readability.

Code Cleanup:

• Removed the _set_layer_color method and inlined its functionality into _apply_layer_color, as it was no longer needed.
• Eliminated the _reset method from its previous location and moved its functionality into a new definition, aligning it with the refactored _update_layer_colors logic. [1] [2]

[zoccoler]

Hi @jo-mueller ,

That's great! Thinks seem to be working! I found only one new bug:

When I draw a cluster, then change the Hue to something non-categorical, and draw again, the MANUAL_CLUSTER_ID is brought back correctly, but my first selection is lost.

[jo-mueller]

Argh ok if I'm only making it worse with my refactorings then maybe we should just merge #390 and then take it from there 😅.