Add display name to Views block placeholder

Problem/Motivation

I was creating a View with 2 block displays to use on the Umami term page. One display would show Recipes and the Articles for the term.

Since they are both in the same view their placeholders are both the same.

You can see here that you can tell which display it is by configuring the block but otherwise you can't

Proposed resolution

Add the display name to the placeholder.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet