feat: improve on api structure, add openapi tags (#2295)

this logically groups api endpoints and gioves them specific openapi tags. which makes them nice on the `/docs` endpoint and makes the `api.py` more approachable
* add wallets list endpoint
* remove trailing slashes from endpoints
* fixup topup url
* fix trailing slash on auth
* backwards compatibility

tests/conftest.py

@@ -20,7 +20,7 @@ from lnbits.core.crud import (
 )
 from lnbits.core.models import CreateInvoice
 from lnbits.core.services import update_wallet_balance
-from lnbits.core.views.api import api_payments_create_invoice
+from lnbits.core.views.payment_api import api_payments_create_invoice
 from lnbits.db import DB_TYPE, SQLITE, Database
 from lnbits.settings import settings
 from tests.helpers import (