Use CAPI operator to manage providers

[eromanova]

This PR introduces the following changes:

1. Add CAPI operator sub chart to HMC. The CAPI operator requires the cert-manager to be installed, thus, this subchart is disabled by default and will be enabled by the HMC controller once the cert-manager is ready. It's also allowed to disable the CAPI operator shipped with HMC to support an external CAPI operator installation.
2. Rework cluster API, cluster API provider AWS, and k0smotron templates to use CAPI operator resources.
3. Change AWS credentials secret data to follow the format required by the CAPI operator.
4. Allow passing providers configuration options in the secret.
5. Change docs accordingly.
6. Added CAPZ template (enabled by default).

Providers configuration

The CAPI operator allows passing configSecret with all the configuration variables: https://doc.crds.dev/github.com/kubernetes-sigs/cluster-api-operator/operator.cluster.x-k8s.io/InfrastructureProvider/[email protected]#spec-configSecret

HMC provider templates were adapted to either pass a pre-created configuration secret name and namespace or receive the configuration parameters as helm chart values (the secret with the provided configuration will be automatically created). This PR introduces the common structure for passing providers' additional parameters.

Examples:

1. To pass the pre-created configuration secret, set:

configSecret:
  name: variables-secret-name
  namespace: variables-secret-namespace // optional. Defaults to `hmc-system`

2. To pass the configuration as a helm value and create a secret with the configuration automatically, set:

configSecret:
  create: true
  name: variables-secret-name // required 
  namespace: variables-secret-namespace // optional. Defaults to `hmc-system`
config:
  CAPI_INSECURE_DIAGNOSTICS: "true"

3. If no overrides for the provider are required and the configSecret configuration is unset, the provider will be deployed with the defaults.

Closes #214
Closes #215