Previous v1beta4 work added support for
ClusterConfiguration.EncryptionAlgorithm, however the possible
values were limited to just "RSA" (2048 key size) and "ECDSA" (P256).
Allow more arbitrary algorithm types, that can also include key size
or curve type encoded in the name:
"RSA-2048" (default), "RSA-3072", "RSA-4096" or "ECDSA-P256".
Update the deprecation notice of the PublicKeysECDSA FeatureGate
as ideally it should be removed only after v1beta3 is removed.
Add v1beta4.ClusterConfiguration.EncryptionAlgorithm field (string)
and allow the user to configure the cluster asymetric encryption
algorithm to be either "RSA" (default, 2048 pkey size) or "ECDSA" (P-256).
Add validation and fuzzing. Conversion from v1beta3 is not required
because an empty field value is accepted and defaulted to RSA if needed.
Leverage the existing configuration option (feature gate) PublicKeysECDSA
but rename the backend fields, arguments, function names to be more
generic - EncryptionAlgorithm instead of PublicKeyAlgorithm.
That is because once the feature gate is enabled the algorithm
configuration also applies to private keys. It also uses the kubeadm API
type (string) instead of the x509.PublicKeyAlgorithm enum (int).
Deprecate the PublicKeysECDSA feature gate with a message.
It should be removed with the release of v1beta4 or maximum one release
later (it is an alpha FG).
Running "go test ./cmd/kubeadm/app/..." results in these 3 files
being generated, since we have more callers to the functions
for generating unique private keys during pkiutil tests.
Add the files to ensure they are not generated locally all the time.
