added configurable log levels

[mertkayhan]

Q	A
Bug fix?	no
New feature?	yes
API breaks?	no
Deprecations?	no
Related tickets	-
License	Apache 2.0

What's in this PR?

Added adjustable logging level for the operator. (All levels supported by zapcore are included.)

Why?

We can produce less logs, especially if we know that our setup is working, and concentrate on errors/warnings in the logs.

Additional context

Checklist

• [ ] Implementation tested
• [ ] Error handling code meets the guideline
• [ ] Logging code meets the guideline
• [ ] User guide and development docs updated (if needed)
• [ ] Append changelog with changes

To Do

• [ ] If the PR is not complete but you want to discuss the approach, list what remains to be done here