[UX] distinguish single url and dynamic url layout groups on layout list

Description of the need

In issue #4839 - we are discussing user confusion over how the default "Home Page" layout in core is applied, especially when the default home page setting has been changed.

@philsward - suggested that creating some distinction between single page layouts and multi page layouts might better help users understand what is happening. I'm opening this ticket to discuss that idea, which goes well above and beyond my simple (short term) suggestion for a change in help text.

Proposed solution

Proposal by @philsward

Discussing this a bit with @stpaultim on Zulip after running into the same problem myself, I've realized there's a problem with how the "single page" layouts are bundled with the "multi-page" layouts.

I think a better UX would be a separation of single page layouts that override a single path, vs multi-page layouts that override multiple pages.

My recommendation is to do a check against the path and search for the wildcard. If none exists, assume it is a single page layout. If it does exist, assume it is a multi-page layout.

From here, I would separate the layouts page into two tabs: Single Page Layouts and Multi-page Layouts