* (WIP) Alerting: Decrypt secrets before sending configuration to the remote Alertmanager
* refactor, fix tests
* test decrypting secrets
* tidy up
* test SendConfiguration, quote keys, refactor tests
* make linter happy
* decrypt configuration before comparing
* copy configuration struct before decrypting
* reduce diff in TestCompareAndSendConfiguration
* clean up remote/alertmanager.go
* make linter happy
* avoid serializing into JSON to copy struct
* codeowners
* Add notification settings to storage\domain and API models. Settings are a slice to workaround XORM mapping
* Support validation of notification settings when rules are updated
* Implement route generator for Alertmanager configuration. That fetches all notification settings.
* Update multi-tenant Alertmanager to run the generator before applying the configuration.
* Add notification settings labels to state calculation
* update the Multi-tenant Alertmanager to provide validation for notification settings
* update GET API so only admins can see auto-gen
* Alerting: Add metrics to the remote Alertmanager struct
* rephrase http_requests_failed description
* make linter happy
* remove unnecessary metrics
* extract timed client to separate package
* use histogram collector from dskit
* remove weaveworks dependency
* capture metrics for all requests to the remote Alertmanager (both clients)
* use the timed client in the MimirAuthRoundTripper
* HTTPRequestsDuration -> HTTPRequestDuration, clean up mimir client factory function
* refactor
* less git diff
* gauge for last readiness check in seconds
* initialize LastReadinesCheck to 0, tweak metric names and descriptions
* add counters for sync attempts/errors
* last config sync and last state sync timestamps (gauges)
* change latency metric name
* metric for remote Alertmanager mode
* code review comments
* move label constants to metrics package
