Add loadpoint config api (BC)

[naltatis]

Continues #12958. Fix #12903

This PR deprecates the following yaml loadpoint settings:

• mode
• title
• phases
• min/max current
• priority

TODO

• UI for loadpoint properties @naltatis
• UI for adding/changing charger @naltatis
• UI for adding/changing lp meter @naltatis
• e2e tests @naltatis
• add translations @naltatis
• UI default vehicle select @naltatis
• UI circuit assignment @naltatis
• API for assignable circuits @andig
• API set meter, charger, defaultVehicle @andig
• UI for adding/removing loadpoints @naltatis
• API for adding/remove loadpoints @andig
• implement config as settings
• unable to save priority=0 @andig
• remove orphan meters/chargers (no site/loadpoint ref) on startup
• fix unit tests @andig
• fix initial lp saving issue (logger, settings) @andig
• store loadpoint settings in config (based on chore: persist device details as json #15224) @andig
• handle pointer values like smartcostlimit
• decide/adapt migration strategy (use evcc migrate?) @andig @naltatis
  • evcc migrate --reset removes all ui configured entities (vehicles, meters, chargers, loadpoints)
  • migrating these entities from yaml to ui will be done in a separate issue later
• demo mode solution @naltatis
• loadpoint settings adapter (config & runtime values) @andig
• no phase option when single-phase (switch socket)