feat: Set Default Value for AdminState and Enhancements for Cron Scheduler

[jackchenjc]

closes: #915

• Make AdminState as an optional field with UNLOCKED as default value
• Enhance the models and DTOs for Cron Scheduler service

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Codecov Report

Attention: Patch coverage is 66.66667% with 10 lines in your changes missing coverage. Please review.

Project coverage is 67.33%. Comparing base (e25b965) to head (83d3b8d).

Files	Patch %	Lines
dtos/schedulejob.go	76.92%	4 Missing and 2 partials :warning:
models/device.go	0.00%	4 Missing :warning:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #916 +/- ## ========================================== - Coverage 67.34% 67.33% -0.02% ========================================== Files 103 104 +1 Lines 4245 4274 +29 ========================================== + Hits 2859 2878 +19 - Misses 1141 1149 +8 - Partials 245 247 +2 ```

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