WIP: Integrate checks

[christophlehmann]

Adds good old caretaker checks

Checks/Resolvers:

[x] Configuration value [x] Extension version [x] Extension state [x] Core version [x] HTTP Headers (Pass full client response to resolvers) [x] Backend users which should be inactive

Others: [x] Better overview for rules? Currently they just extend the extra fields in client table [x] Handle failed rules (client is missing needed providers and does not return needed data) [ ] Labels

For review use https://github.com/christophlehmann/t3monitoring_client/tree/add-check-provider as client