feature request - support db store for accounts

[Anhui-tqhuang]

when deploying the nats-account-server on kubernetes, we should make sure we don't lose accounts though we have three replicas and PVC setup.

it's not easy to setup a backup-restore strategy on pvc with low RPO and RTO, i wonder would it be possible to add a new db store like postgresql, as a result, it would be much easier for recovery.

[aricart]

@Anhui-tqhuang the current nats-server supports the nats resolver which effectively allows the cluster to synchronize configurations, unless you have a need to have an HTTP endpoint for doing updates, you should not be using the nats-account-server.

[Anhui-tqhuang]

@aricart hey, thanks for the reply!, if i use nats resolver, i still needs to consider how to backup-restore data kept in the PV, if it's possible to use DB as store for nats resolver?