Key store: Support stack updates

See [Editing CloudHSM key store](https://docs.aws.amazon.com/kms/latest/developerguide/update-keystore.html)

Implement an update state machine to support:
* Renaming key store
* Disconnecting and reconnecting the key store in support of maintenance operations
* Informing KMS of an update to the `kmsuser` password in support of common operations
* Disconnecting the key store and reconnecting it to a different CloudHSM cluster
* For example, in support of connecting to a CloudHSM cluster created from a backup
* Changing the option to delete the key store upon stack deletion