Shared Filesystems can't be deployed on local-only storage due to "HA" requirement

### problem

The Shared Filesystem appliance requires a "HA enabled" compute offering - and it's not a bad idea, but in cloud with local storage only this becomes a problem as it's pointless to add HA=true to an offering on local storage and could also lead to other possible issues in Cloudstack internally (who knows..).

Is it worth adding a global option, such as "sharedfs.ha.required" and set it to yes/no depending on what storage you are running?

### versions

4.20 KVM

### The steps to reproduce the bug

Deploy Filesystem Share without HA enabled compute offering.

### What to do about it?

Discuss and maybe implement an extra global option to require or not HA in offerings.

Start with the Shared Filesystem appliance deployment path and the validation that requires an HA-enabled compute offering. Reproduce deployment using local-only storage and an offering without HA, then trace how the requirement is applied. Done means the behavior can be configured for local storage while preserving the current HA requirement where it is needed.

Written by the indexing model from the issue text.