[4.x] Add entry and term empty view permission checks

[jacksleight]

This PR adds permission checks to the entry and term empty views, so that these options only appear if you have permission to access them:

If you don't have permission to access anything it shows a simple placeholder:

Additionally this PR includes three related changes:

1. The scaffold index method now requires the same permission as the scaffold create method, since there's no point in being able to access the form if you can't submit it.
2. Adds a Configure Blueprints option to the empty terms view.
3. The docs link on the empty term view has been moved to a callout style box at the bottom, which matches how the entry and collection/taxonomy views do it.