Custom color provider example

[Simard302]

Overview

This PR creates a new example for inspecting a new structure and listing the types of interactions made between a selection and the structure

Changes made

• Created coloring example "custom_color_provider"
  • Creates a custom color theme that will color Alt Loc atoms based on their Alt Loc ID

How to test

Ensure the alt loc atoms are colored differently.

Specific review requests

For each of the examples:

• Are there enough comments to sufficiently describe the process?
• Are the comments accurately describing the process?
• Are there any anti-patterns in the examples?
• Can the examples be more efficient?