fix: Add target ping interval & Add parameter validation for config

[destinyoooo]

This PR includes the following improvements:

1. Add target ping interval ：

   • Added pingInterval field in target.go, defaulting to 30 seconds
   • Implemented ping caching mechanism, only ping the database when the last ping was more than pingInterval ago
   • Reduced unnecessary ping operations to the database, especially when using cached collectors

2. Add parameter validation for config ：

   • Enhanced checkRequiredFields method in config/config.go
   • Validated target configuration to ensure data_source_name and collectors fields exist
   • Validated jobs configuration to ensure job_name, collectors, static_configs, and targets fields exist

[burningalchemist]

Hey @destinyoooo, thank you for your contribution! 👍

Overall looks good, but do you mind splitting the PR in two? The scope is a bit different for these, and I'd like to keep changes scoped.

[destinyoooo]

This PR includes the following improvements:

1. Add target ping interval ：

   • Added pingInterval field in target.go, defaulting to 30 seconds
   • Implemented ping caching mechanism, only ping the database when the last ping was more than pingInterval ago
   • Reduced unnecessary ping operations to the database, especially when using cached collectors

2. Add parameter validation for config ：

   • Enhanced checkRequiredFields method in config/config.go
   • Validated target configuration to ensure data_source_name and collectors fields exist
   • Validated jobs configuration to ensure job_name, collectors, static_configs, and targets fields exist

Of course, I have already completed it. In #948 and #949

[burningalchemist]

Thanks! 👍 Closing this one in favour of #948 and #949.