(Angular) Style widgets using CSS variables.

[ditman]

Description

This PR adds styling based on CSS variables to the components of the basic catalog of the Lit renderer.

The PR uses the base styles defined in web_core, and adds per-component overrides that can be used to customize the appearance of each component further.

• Continues [RFC] Core v0.9 styling #1057.
• The Angular version of (Lit) Style widgets using CSS variables. #1079

Testing

• Tested manually by running npm run demo in the angular renderer directory.

Pre-launch Checklist

• I signed the CLA.
• I read the Contributors Guide.
• I read the Style Guide.
• I have added updates to the CHANGELOG.
• I updated/added relevant documentation.
• My code changes (if any) have tests.

If you need help, consider asking for advice on the discussion board.

[gemini-code-assist]

Code Review

This pull request implements a comprehensive theming refactor for the v0.9 basic catalog components across both Angular and Lit renderers, replacing hardcoded styles with a system of CSS variables. Key changes include the introduction of a base class for Lit components to handle style injection, the removal of the minimal catalog, and standardized layout mapping for Row and Column components. Review feedback highlights several areas for improvement, including the removal of as any type assertions, addressing potential style leakage from global encapsulation in Angular, deduplicating layout constants, and resolving inconsistencies in icon naming logic and documentation between the two frameworks.

[ditman]

(Please ignore anything outside renderers/angular, that's part of a previous PR but stacking is not great)