SearchVisualizer: New feature show_only_solution_path and fixing tapered_search_layer_heights

[EliasLF]

Description

• Adding a new option to the search graph visualizer to only show the final solution path in each layer (intended for large, convoluted search trees and situations where only the final solution is of interest)
• Fixing a minor bug that rendered the option tapered_search_layer_heights ineffective in many cases

Checklist:

• The pull request only contains commits that are related to it.
• I have added appropriate tests and documentation.
• I have made sure that all CI jobs on GitHub pass.
• The pull request introduces no new warnings and follows the project's style guidelines.

[burgholzer]

LGTM 👍🏻