Issue #3471956 by joshua1234511, richardgaunt, fionamorrison23: Enhance Civictheme menu theming system

[joshua-salsadigital]

https://www.drupal.org/project/civictheme/issues/3471956

Checklist before requesting a review

• I have formatted the subject to include ticket number as Issue #123456 by drupal_org_username: Issue title
• I have added a link to the issue tracker
• I have provided information in Changed section about WHY something was done if this was not a normal implementation
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have added tests that prove my fix is effective or that my feature works
• I have run new and existing relevant tests locally with my changes, and they passed
• I have provided screenshots, where applicable

Changed

1. Modified the preprocess to set theme based on theme hook set in configuration.

Steps to Create and Style a New Menu in CivicTheme

Step 1: Create a New Menu in Drupal

1. Navigate to Structure → Menus → Add Menu.
2. Enter a Title (e.g., "CivicTheme Sidebar Navigation").
3. Add Menu Links as needed.
4. Save the menu.

Step 2: Place the Menu in a Block

1. Go to Structure → Block layout.
2. Click Place Block in the desired region.
3. Search for the menu you created and select it.
4. Under HTML and Style Options, set the Theme Hook Suggestion to one of the following:
   civictheme_primary_navigation
civictheme_secondary_navigation
civictheme_footer
5. Save the block placement.