(chore) Ease the process of adding mutliple validation of ChaosEngine

[rahulchheda]

Signed-off-by: Rahul M Chheda rchheda@infracloud.io

What this PR does / why we need it:

• Purpose of this PR is to ease the process of defining the functions for validation on ChaosEngine Object(as a template is now available in form of annotationCheck).
• This help to standardize the function definition, and help in collecting the errors produced by them.

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #

Special notes for your reviewer:

How does this PR help?

So, for example, a contributor wants to add a function for the validation of namespace.

Steps needed to be performed:

• Need for a function definition with syntax similar to this one func namespaceValidation(ce *crv1alpha1.ChaosEngine) error is to be defined.
• And then append this function name to this line https://github.com/litmuschaos/admission-controllers/pull/10/files#diff-2351c76b931b04dcaa68b4d83b8cb372R200, which looks something like: err = wh.CollectValidationErrors(&chaosEngine, wh.ValidateChaosTarget, wh.namespaceValidation)

Checklist:

• [ ] Fixes #
• [ ] Labelled this PR & related issue with documentation tag
• [ ] PR messages has document related information
• [ ] Labelled this PR & related issue with breaking-changes tag
• [ ] PR messages has breaking changes related information
• [ ] Labelled this PR & related issue with requires-upgrade tag
• [ ] PR messages has upgrade related information
• [ ] Commit has unit tests
• [ ] Commit has integration tests

[ksatchit]

Looks good @rahulchheda . Wondering if we should rename this file to a more generic appFilterCheck over annotationCheck - considering we now have the option to skip appinfo completely OR run w/ annotationCheck disabled