Config UI: improve device updates

[naltatis]

Improves device status update on config page.

⏳ resepect interval setting for status update cycle (before 10s) to prevent overloading sensible devices
♻️ update devices sequentially to reduce concurrent network calls
🚪 ensure status updates are stopped when leaving config page

[andig]

resepect interval setting for status update cycle (before 10s) to prevent overloading sensible devices

Das ist Aufgabe der Devices, im Zweifel durch Caching. Ansonsten LGTM.