Add card to main card list so it can be selected via the "Add Card menu

[thybag]

Only just realised the card doesn't actually show in the "add card" menu. I've made a few tweaks to fix this.

• Card is now registered with the "add card" menu including a preview
• Basic stub is setup, so defaults to including all entities with lng/lat info.
• Fixed a bug where history didn't work if you only set a history_start (as history_end defaults to null)

[thybag]

I'm not entirely what steps are needed to resolve the Error: <Plugin thybag/ha-map-card> Repository structure for add-to-card-list is not compliant I'm getting from the HACS stuff 😬

[nathan-gs]

You can ignore the hacs errors (will see if I can fix them for forks).