Integrate external cluster creation with Krew

[parth-gr]

In the recent scenario, there are a lot of cases regarding the steps needed to create external-cluster,
As the scenario is very-complicated because it includes both consumer and producer at separate ends,

Which makes the user not understand some of the steps,
Integrating with krew will let it boils down to just a single command,

So opening this issue so we can discuss what all changes needed to be done.

Updating the slack discussion: https://rook-io.slack.com/archives/CK9CF5H2R/p1665464169001099

[obnoxxx]

@parth-gr could we use a rook-managed ceph cluster as external cluster to connect to?