Add *explicit* support for Personal Tokens

Added a toggle to use the legacy application API key -- migration makes sure this toggle starts enabled if upgrading from an older version that was already set up.

Personal Tokens currently work with the API-Key header (I assume for backwards compatibility) - I could not find documentation for this nor know if the reverse is true. Thus why I added the toggle, plus some additioanl text explaining why a little.

Also updated the link to just go straight to the dashboard instead.