Adds flags for management- and service-cluster bools, and marks the two
mutually exclusive.  If either are provided, then --cluster-id is
required as well.

This is setting groundwork for HCP MC and SC support.

Signed-off-by: Chris Collins <[email protected]>

* Adds `--manager` and `--service` flags to allow logging into MC/Hive and SC clusters for a provided `--cluster-id`.
* Adds related and other helpful ENV vars inside the container
* Adds `--namespace` flag to override the default NS on whatever cluster is being logged into
* Removes login logic from ~/.bashrc.d/* files inside the container, moving the responsibility of login to ocm-container's binary

WIP - TODO:

* Add a log message immediately before spawning login execs so users will have positive feedback on why they're waiting.  This used to be incidental as a result of the different bash scripts, making it feel like login wasn't just hanging, but even though it's the same length if ocm-container executes the login, because there's no feedback it feels like ocm-container has hung.
* Figure out how to perform the login to ocm and backplane in order, but async from the container attachment, to speed up the login.
* Do the plumbing to pick the right cluster if `--manager`, `--service` or `--namespace` are provided.

Signed-off-by: Chris Collins <[email protected]>

Signed-off-by: Chris Collins <[email protected]>

Signed-off-by: Chris Collins <[email protected]>

Signed-off-by: Chris Collins <[email protected]>