Move the three pillars of observability into core - logging

This is an implementation issue to move our logging within the Monitor stage into Core

This should have a separate MR to update our documentation as well

Checklist

MR breakdown	location	destination	what to move
1	/ee/app/models/ee/clusters/platforms/kubernetes.rb	app/models/clusters/platforms/kubernetes.rb	backend read_pod_logs and other dependencies see code
2	/ee/config/routes/project.rb	/config/routes/project.rb	backend resources :logs path see code
2	/ee/lib/ee/gitlab/etag_caching/router.rb	ee/lib/ee/gitlab/etag_caching/router.rb	backend route etag caching regex see code
2	ee/app/serializers/ee/environment_entity.rb	-	backend project_path and enable_advanced_logs_querying (if still needed after refactoring)
3	/ee/app/services/pod_logs_service.rb	/app/services/pod_logs_service.rb	backend service + specs
3	/ee/app/controllers/projects/logs_controller.rb	/app/controllers/projects/logs_controller.rb	backend controller + specs
4	/ee/app/assets/javascripts/logs	/app/assets/javascripts/logs	frontend entire vue dir
4	/ee/spec/frontend/logs	/spec/frontend/logs	frontend entire specs dir
4	/ee/app/views/projects/logs/	/spec/frontend/logs	frontend entire haml dir
5	/doc/user/project/clusters/index.md	-	documentation ultimate tag
5	/doc/user/project/clusters/kubernetes_pod_logs.md	-	documentation ultimate tag

Breakdown

• 1 #198455 (closed)
• 2 #198454 (closed)
• 3 #198453 (closed)
• 4 #198452 (closed)
• 5 #198451 (closed)

Technical Requirements

• We should refactor logs according to #39092 (closed) in order to avoid conflicts when moving to core.