Support creating, deleting and updating individual flows from the CLI

[Melkaz]

Feature description

Use-case: a flow needs to be created, deleted or updated from the CLI

Expected behavior:

• When creating a new flow, the file should be pushed to the server. If a flow with the same id already exists, it should fail.
• When deleting a flow, the id parameter should be used to remove it from the server. If the id is unknown, it should fail.
• When updating a flow, the file should be pushed to the server and the flow with the same id, replaced. Ideally, the revision number should be increased. If the id is unknown, it should fail.

Thanks :)