Theme Layout Builder Modal and Media Library to look like Claro admin theme

I was thinking of this enhancement and we need to make sure of the following:

• Add a hook update to make sure Claro theme is enabled. Because older Varbase sites might not have Claro enabled, and this will potentially break.
• Add an if statement to check if Claro theme is enabled in VarbaseLayoutBuilderThemeNegotiater
• Add Drupal version requirement to the Varbase Layout Builder. We need to make sure we're using Drupal core when it actually has the Claro theme in core.

This will ensure a fault tolerant implementation, so when older Varbase sites update to the most recent version of Varbase Layout Builder, and their config still uses the older Vartheme Adminimal, they can still use these feature effectively.