Ability to add provider specific featureGates with Helm

[oprinmarius]

User Story

As a operator I would like to have the ability to add provider specific featureGates.

Detailed Description
Currently manager featureGates are only added to the InfrastructureProvider.
There is no option to add featureGates to CoreProvider (eg. MachinePool)
Adding all featureGates to CoreProvider will often break the deployment because of provider specific featureGates that are not compatible with the CoreProvider (eg. EKSEnableIAM ).

Example:

• Add support for provider specific featureGates
  6c9e585

• Add featureGates to CoreProvider
  fa051d4

values.yaml:

manager:
  featureGates:
    core:
      ClusterTopology: true
      MachinePool: true
    aws:
      EKSEnableIAM: true
      EKSAllowAddRoles: true
      ClusterTopology: true
      MachinePool: true

/kind feature

[alexander-demicev]

/triage accepted