R4R: Support "unknown commands" for subcommands

[colin-axner]

Fixes #4284
Now prints:

gaiacli query distr comission --trust-node cosmos1234
ERROR: unknown command "comission" for "distr"

Did you mean this?
	commission

Adds custom argument validation for subcommands with subcommands. Doesn't affect "query" or "tx" subcommands since they reside in gaia repo. All flags except help are disabled for these commands

• Targeted PR against correct branch (see CONTRIBUTING.md)

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.

• Wrote tests

• Updated relevant documentation (docs/)

• Added a relevant changelog entry: clog add [section] [stanza] [message]

• rereviewed Files changed in the github PR explorer

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For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@52be449). Click here to learn what that means.
The diff coverage is 76.47%.

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[alexanderbez]

TestedACK

[alessio]

Lovely, thanks!