Improve ergonomics for clients connecting to cluster on another host

[tjtelan]

The default Rust client assumes a local cluster, with preference given to the config file at ~/.fluvio/config.

You can also connect to a different cluster by providing a FluvioConfig.

But for the CLI and our other clients, users need to modify ~/.fluvio/config to connect to another cluster, which is not always a practical approach.

In my opinion this behavior was permitted by Profile (and maybe also Config) being heavily leveraged in the fluvio crate. It enabled shortcuts for the CLI that other clients don't need to assume. Like having a config file to load from a specific location on the filesystem.

---

What I think needs to happen:

• Move the whole concept of Profile (and maybe Config too?) out of fluvio and into fluvio-cli-common (or related crates), since it is effectively a CLI only concept for a user of multiple clusters. Not directly used by Fluvio cluster.
• Add CLI subcommands to add new Profiles so users don't have to open the file
• Expose FluvioConfig in the other language client libraries, so it can be used to connect to other clusters (or add other connect methods to provide the same effect)
  • This point is not to be solved by this issue. The other clients can link to this issue