Several meta capabilities have no handling in map_meta_cap()

[johnbillion]

The following meta capabilities are used within core but do not have any handling (no case statement) in map_meta_cap(). While this is functionally fine, it does mean that it's not possible to complete the meta capability tests in #38191.

• create_sites
• delete_sites
• manage_network
• manage_sites
• manage_network_users
• manage_network_plugins
• manage_network_themes
• manage_network_options

Meta capabilities with no handling in map_meta_cap() fall back to requiring a primitive capability of the same name, so this is the functionality that should occur in map_meta_cap(). This has no functional change as these capabilities are only available to super admins.

[johnbillion]

In 38695:

Role/Capability: Add explicit cases to map_meta_cap() for various meta capabilities that are used in core. This will allow more complete meta and primitive capability unit tests in #38191.

Fixes #38201