Add ForceSemverUpgradeConstraints feature gate

[m1kola]

Please read RFC for better formatting and full scope. The excerpt below is just to indicate the scope covered by this specific issue.

We need to implement a feature gate as per RFC:

Need a feature gate to switch between two upgrade constraint semantics. When:

• Disabled - operator-controller uses legacy semantics
• Enabled (default) - operator-controller uses semver

The feature gate can be enabled or disabled by passing the following flag to the manager binary:

--feature-gates=ForceSemverUpgradeConstraints=true

This functionality will be built on top of operator-controller’s existing feature gate mechanisms which is based on the k8s.io/component-base/featuregate package.