[Feature]: Refactor Parameter Validations in Resolvers' main() Functions

[openhands-agent]

What problem or use case are you trying to solve?
Parameter validations in each resolver's main() function should be refactored to use a shared code from the utils library to promote code reusability and maintainability. The current implementation across multiple resolver files lacks consistency.

Desired UX of the solution
Refactored validations within the resolver functions would use a shared utility from the utils module. The reusable utility should ensure consistent parameter validation and reduced code duplication.

Technical implementation
The shared utility function can be added to the utils module. Each resolver's main() function should then replace the current ad-hoc validation logic with the utility function.

Alternatives considered
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Additional context
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Issue Created By: tawago on Slack
Link to Slack Thread: https://openhands-ai.slack.com/archives/C078L0FUGUX/p1743155016537279?thread_ts=1743155016.537279&cid=C078L0FUGUX