Mutating webhook cleanup

Over time, mutating webhook has gone through several feature changes. Specifically, following features are no longer supported.

1. Checking Pod-level policies
2. Checking and applying Namespace-level policies (func checkAndApplyNSPolicies)
3. Checking and applying Service-level policies (func checkServiceLevelPolicyApplicability)
4. Finding root of a custom resource instance (func findRoot)
5. Getting API details from Helm release annotation (func getAPIDetailsFromHelmReleaseAnnotation)
6. Applying policies (func applyPolicies)
7. Getting Field value from instance (func getFieldValueFromInstance)
8. Commented parts from register man page (func registerManPage)
9. Use of guuid variable and customAPIInstanceUIDMap
10. Setting owner references (func setOwnerReference)
11. Update owner reference (func updateOwnerReference)
12. Handling binding functions (func getSpecResolvedPatch)
13. Searching annotations (func searchAnnotation)

This issue is to track removal of these functions/parts from the code.