Allow Branch Menu blocks to be used on Branch subpages

Problem/Motivation

Currently, the Branch Menu is only usable on Branch pages, but in order to create a cohesive structure for each Branch section of the site (a Branch page and subpages, created using LB Landing Pages), the Branch Menu block needs to be able to be used on Landing Pages. This will require the block to manually reference the parent Branch (using the URL path might be possible, but more complex and not as reliable).

Steps to reproduce

Attempt to add the Branch Menu to a non-branch page.

Proposed resolution

• Add an entity reference field to the branch menu block which allows editors to select the related branch.
• modify the existing logic to pull the appropriate menu links from the referenced branch page

Remaining tasks

User interface changes

API changes

Data model changes