chore: improve argument handling and error messages

[tstirrat15]

Written with LLM assistance.

Description

I ran into this when I fatfingered a zed permission lookup-resources today. The error looks like this:

❯ zed permission lookup-resources thumper/user:someuser view thumper/resource
5:56PM ERR terminated with errors error="the length of the unpacked is not equal to the provided input"

Which is cryptic and doesn't indicate where the issue is - it sounds like it could as easily be a gRPC internal error as a malformed input error.

This PR improves the error output so that it points at the specific arg and provides a template.

Changes

• Add more parsing helpers and improve existing parsing helpers
• Use those parsing helpers
• Tests for parsing helpers
• Test of overall command

Testing

Review. See that tests pass. do go run ./cmd/... permission lookup-resources thumper/user:someuser view thumper/resource and see that you get more useful output.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 80.43478% with 9 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
internal/commands/permission.go	25.00%	8 Missing and 1 partial ⚠️

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