refactor: extract validation and waitFor parsing helpers

[Syedowais312]

Summary

Refactors the test command implementation by extracting:

• argument validation logic
• --waitFor parsing logic
• duplicated error messages

into reusable helper functions.

Changes

• Added validateTestCommandArgs()
• Added parseWaitForMilliseconds()
• Added parseWaitForValue()
• Centralized repeated error strings into constants
• Removed duplicated parsing/validation code
• Fixed variable shadowing for testResultID

Benefits

• Improves readability
• Reduces duplicated logic
• Makes validation easier to maintain and test

[github-actions]

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