feat: support for numeric operators

[yashvardhan-kukreja]

Signed-off-by: Yashvardhan Kukreja yash.kukreja.98@gmail.com

Related issue

#1512

What type of PR is this?

/kind feature

Proposed changes

The newly added operators which can be applied to validate.deny.conditions and preconditions over kyverno policy rules are the following:

• GreaterThanOrEquals : key >= value?
• GreaterThan : key > value?
• LessThanOrEquals : key <= value?
• LessThan : key < value?

Checklist

• I have read the contributing guidelines.
• I have added tests that prove my fix is effective or that my feature
  works.
• I have added or changed the documentation.

Further comments

Here, the key will only be expected to be int, int64, float, float64, string (for the cases like "2", "2.4" only)
In rest of the cases, an error with saying "Unknown key type found" would be generated because clearly, these are numeric operators and these operations can't be applied on types which can't be casted to int or float.

[yashvardhan-kukreja]

@JimBugwadia for now I have implemented the support for GreaterThanOrEquals operator. Please give it a look and if it looks fine, I'll implement GreaterThan, LessThan and LessThanOrEquals operators as well in the same way.

[JimBugwadia]

@yashvardhan-kukreja - looks good! I would suggest factoring out reusable code wherever possible as you implement the other operators. This package seems to have a lot of duplication we can improve. Thanks!

[yashvardhan-kukreja]

@yashvardhan-kukreja - looks good! I would suggest factoring out reusable code wherever possible as you implement the other operators. This package seems to have a lot of duplication we can improve. Thanks!

True. I was thinking of creating one NumericOperatorHandler which will handle the work of all the GreaterThanOrEquals, GreaterThan, LessThan, LessThanOrEquals operators.

[yashvardhan-kukreja]

@JimBugwadia @realshuting I have implemented a generic NumericOperator which will help in dealing with all the numeric operations. PTAL and let me know if it looks fine.
Thanks :)

[realshuting]

Looks good!

[realshuting]

Please use closing keywords in the pull request's description, the issue will be closed when merging into the default branch.