Add support for testing Vault Enterprise with HA seal support by adding
a new `seal_ha` scenario that configures more than one seal type for a
Vault cluster. We also extend existing scenarios to support testing
with or without the Seal HA code path enabled.
* Extract starting vault into a separate enos module to allow for better
handling of complex clusters that need to be started more than once.
* Extract seal key creation into a separate module and provide it to
target modules. This allows us to create more than one seal key and
associate it with instances. This also allows us to forego creating
keys when using shamir seals.
* [QT-615] Add support for configuring more that one seal type to
`vault_cluster` module.
* [QT-616] Add `seal_ha` scenario
* [QT-625] Add `seal_ha_beta` variant to existing scenarios to test with
both code paths.
* Unpin action-setup-terraform
* Add `kms:TagResource` to service user IAM profile
Signed-off-by: Ryan Cragun <me@ryan.ec>