Initial round of eslint fixes.

https://www.drupal.org/project/admin_toolbar/issues/3564892

Admin Toolbar: Fixed all ESLINT validation errors.

• Applied automatic fixes with the --fix flag in the command.
• Fixed remaining errors manually, mostly:
  • Assigned names to unnamed functions.
  • Add basic @jsdoc doc comment blocks documentation.
  • Wrapped JS code in once call to prevent multiple executions.
• Refactored with Vanilla JS the logic for removing menu links tooltips.
• Removed the last two blocks of unneeded jQuery logic.

 
Additional change related to issue #3564229 and MR !193 (merged):
Admin Toolbar Search: Removed the JS logic preventing the Front page, with URL /, from appearing in search results suggestions.