test: add robot tests for cli tab completions

[jarhodes314]

Proposed changes

Add some tests which verify tedge responds correctly to a shell completion request. These tests simulate the command that fish uses when requesting tedge completions and checks that the response is the expected list of values and accompanying values. fish output is used as it is very human-readable and includes help text. These tests don't verify that the completion script is installed.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (general improvements like code refactoring that doesn't explicitly fix a bug or add any new functionality)
• Documentation Update (if none of the other choices apply)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Paste Link to the issue

• Add tests for shell completions #3373

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA (in all commits with git commit -s)
• I ran cargo fmt as mentioned in CODING_GUIDELINES
• I used cargo clippy as mentioned in CODING_GUIDELINES
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Additional details and impacted files

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[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
587	1	3	588	99.83	1h35m49.122005999s

Failed Tests

Name	Message	⏱️ Duration	Suite
Tedge has completions for cloud profile names	Multiline strings are different: --- first +++ second @@ -1,4 +1,4 @@ +test other -test azure aws	8.709 s	Tedge Completions