[receivercreator] Validate endpoint's configuration before starting receivers

[ChrsMark]

Description:

The receivercreator should validate the runtime configurations before starting a receiver. This PR adds this validation.

Link to tracking Issue: Fixes #33145

Testing:

Using the following helm chart's values:

mode: daemonset

config:
  extensions:
    k8s_observer:
      auth_type: serviceAccount
      node: ${env:K8S_NODE_NAME}
      observe_nodes: true
  exporters:
    debug:
      verbosity: basic
  receivers:
    receiver_creator/3:
      watch_observers: [ k8s_observer ]
      receivers:
        apache:
          rule: type == "k8s.node"
          config:
            endpoint: "http://localhost:8080/server-status?manual"
  service:
    extensions: [health_check, k8s_observer]
    pipelines:
      metrics:
        receivers: [receiver_creator/3]
        processors: [batch]
        exporters: [debug]

Expect to see an error after the config's validation:

2024-09-25T10:46:56.778Z	error	[email protected]/observerhandler.go:159	failed to start receiver	{"kind": "receiver", "name": "receiver_creator/3", "data_type": "metrics", "receiver": "apache", "error": "invalid runtime receiver config: receivers::apache: query must be 'auto': 'http://localhost:8080/server-status?manual'"}
github.com/open-telemetry/opentelemetry-collector-contrib/receiver/receivercreator.(*observerHandler).OnAdd
	github.com/open-telemetry/opentelemetry-collector-contrib/receiver/[email protected]/observerhandler.go:159
github.com/open-telemetry/opentelemetry-collector-contrib/extension/observer.(*EndpointsWatcher).updateAndNotifyOfEndpoints
	github.com/open-telemetry/opentelemetry-collector-contrib/extension/[email protected]/endpointswatcher.go:111

This stops the execution of the receiver which would lead to fetch errors (as described in the respective issue #33145):

2024-05-21T09:17:46.749Z	error	[email protected]/scraper.go:67	failed to fetch Apache Httpd stats	{"kind": "receiver", "name": "receiver_creator/3", "data_type": "metrics", "name": "apache//receiver_creator/3{endpoint=\"http://localhost:8080/server-status?manual\"}/k8s_observer/kind-control-plane-b75cdcf9-ee9d-4cb8-aa53-1ceb030d898d", "error": "Get \"http://localhost:8080/server-status?manual\": dial tcp [::1]:8080: connect: connection refused"}
github.com/open-telemetry/opentelemetry-collector-contrib/receiver/apachereceiver.(*apacheScraper).scrape
	github.com/open-telemetry/opentelemetry-collector-contrib/receiver/[email protected]/scraper.go:67
go.opentelemetry.io/collector/receiver/scraperhelper.ScrapeFunc.Scrape
	go.opentelemetry.io/collector/[email protected]/scraperhelper/scraper.go:20
go.opentelemetry.io/collector/receiver/scraperhelper.(*controller).scrapeMetricsAndReport
	go.opentelemetry.io/collector/[email protected]/scraperhelper/scrapercontroller.go:194
go.opentelemetry.io/collector/receiver/scraperhelper.(*controller).startScraping.func1
	go.opentelemetry.io/collector/[email protected]/scraperhelper/scrapercontroller.go:169
2024-05-21T09:17:46.750Z	error	scraperhelper/scrapercontroller.go:197	Error scraping metrics	{"kind": "receiver", "name": "receiver_creator/3", "data_type": "metrics", "name": "apache//receiver_creator/3{endpoint=\"http://localhost:8080/server-status?manual\"}/k8s_observer/kind-control-plane-b75cdcf9-ee9d-4cb8-aa53-1ceb030d898d", "error": "Get \"http://localhost:8080/server-status?manual\": dial tcp [::1]:8080: connect: connection refused", "scraper": "apache"}

Documentation:

[ChrsMark]

@dmitryax could you also have a look into this one🙏?