Breadcrumb render cache not invalidated when entity label changes

Problem/Motivation

Cache of entities are not invalidated when the entity label changes.

Steps to reproduce for nodes & breadcrumbs (from #3):

1. Create a node with title 'Title A'.
2. Change the title to 'Title B' and check the 'Create new revision'.
3. Open the Revisions tab > Breadcrumb shows the right title (Title B).
4. Change the title to 'Title C' and check the 'Create new revision'.
5. Open the Revisions tab.

Expected: The title in the breadcrumb is 'Title C'.
Actual: the title in the breadcrumb is 'Title B'.

Steps to reproduce for users (from #48):

1. Log in
2. Edit your username and save.
3. Return to the edit screen for your user account.

Expected: Breadcrumb shows your new username
Actual: You'll see your old username is still utilised in the breadcrumb.

Proposed resolution

Allow attaching cacheability metadata to titles with a new CacheableTitleResolverInterface that returns a static or dynamic title (with cacheable metadata).