[Proposal] Improve and expand charts plugin to become the "Visualization Style Integrator"

[joshuarrrr]

The current charts plugin is lightly and inconsistently used, and provides some miscellaneous utilities for use in visualizations:

1. Color palettes (schemas, maps)
2. Theme fetching services
3. A collection of static visualization option UI components

I propose that we use this as a starting point to build out a primary source of truth for visualization default interactions and styling. It's role would be to combine and resolve:

1. Design system (via OUI) styles and usage guidelines
2. Admin-level theming and chart preferences
3. User-level theming and chart preferences

Potential tasks:

• Downstream visualizations can retrieve semantic colors (color palettes by function) without needing to know anything about various theme or color overrides at the system level
• All existing visualizations use charts when fetching color defaults
• charts plugin contains look and feel style implementations and defaults from OUI
• Migrate static visualization option UI components to new vis_options plugin