Provide a way to mount read-only snapshots via the API

[alaric-dotmesh]

As a Dotscience Agent developer, I want a way to honour requests in task payloads to mount specific versions of datasets, so that I can actually provide the functionality offered by the ds run command...

Therefore, I need a way to ask Dotmesh to provide a read-only mount of a historic snapshot of a dot.

ACs

• [ ] There's an API call to request mounting of a specific snapshot of a filesystem.

Implementation Notes

Perhaps an optional argument to Procure, rather than a new API?

[binocarlos]

@alaric-dotmesh there is a MountCommit RPC call that does this code - it takes the following struct:

args *struct{ FilesystemId, CommitId string }

and returns the mount path the snapshot was mounted to

[alaric-dotmesh]

Perfect! Thanks!