Introduce State Driven Status, use record pkg for event and clean logging

[AdheipSingh]

Fixes #195 Fixes #190

Description

Changes

1. Introduce druid cluster status
2. Use event recorder pkg
3. clean up unnecessary logging
4. zero pollution of events as well as logs, reduces the requests on k8s api
5. state driven status.
6. EventEmitter interface - can be extended in the future to emit events to various backends ( kafka, statsd just like druid does )

Logging

• A delete, and update logs on deletion of CR ( finalizer )

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This PR has:

• [x] been tested on a real K8S cluster to ensure creation of a brand new Druid cluster works.
• [x] been tested for backward compatibility on a real K*S cluster by applying the changes introduced here on an existing Druid cluster. If there are any backward incompatible changes then they have been noted in the PR description.
• [x] added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• [x] added documentation for new or modified features or behaviors.

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Key changed/added files in this PR

• handler.go
• types.go
• status.go
• handler.go

[AdheipSingh]

@himanshug will need your review here.

[himanshug]

sorry, will review it this week.

[AdheipSingh]

@himanshug :)

[himanshug]

I took a quick look today, LGTM

We can merge this if you have already had this deployed on some clusters and it is functioning as expected.

[AdheipSingh]

We can merge this if you have already had this deployed on some clusters and it is functioning as expected.

yes, we have been running this on prod for couple of months.

@nishantmonu51 waiting on you for this.