* variant: move into internal/attestation
* attesation: move aws attesation into subfolder nitrotpm
* config: add aws-sev-snp variant
* cli: add tf option to enable AWS SNP
For now the implementations in aws/nitrotpm and aws/snp
are identical. They both contain the aws/nitrotpm impl.
A separate commit will add the actual attestation logic.
* Add attestation options to config
* Add join-config migration path for clusters with old measurement format
* Always create MAA provider for Azure SNP clusters
* Remove confidential VM option from provider in favor of attestation options
* cli: add config migrate command to handle config migration (#1678)
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Signed-off-by: Daniel Weiße <dw@edgeless.systems>
