cli: Add event stream capture to nomad operator debug

[davemay99]

Adds Event Stream capture to nomad operator debug. Enable -verbose output for realtime feedback on events as they are captured.

New CLI flags:

• -event-filter
• -verbose

Example usage:

nomad operator debug -event-filter="Evaluation:*" -verbose

See Events API documentation for more details on topic filtering.

Closes #11493

[jrasell]

This will be a really nice addition to the bundles, thanks for much @davemay99!

In addition to the review comments, it would be nice to have names against the TODO items within the code. This isn't to point blame, rather if someone without context takes a look into updating this code, they can refer to you for addition information if needed.

Probably out of scope for this PR, but it would be great to have some real world examples of using the debug command that could be quickly referenced. People using this command are usually under pressure, so anything to help I feel would be useful.

[jrasell]

I wanted to note that while giving this information in the CLI is very useful, there is a maintenance cost to pay whereby we will need to update this every time a new endpoint is added to the events stream that would be useful within the debug bundle.

[davemay99]

IIRC all CLI commands include a mention of ACL requirements. Do you have a recommendation on how to reduce that maintenance cost?

[davemay99]

it would be nice to have names against the TODO items within the code

@jrasell Good idea -- I tagged myself on all the TODO items.

[lgfa29]

Changes addressed

[github-actions]

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