feat: support adc server mode

[AlinsRan]

Type of change:

• Bugfix
• New feature provided
• Improve performance
• Backport patches
• Documentation
• Refactor
• Chore
• CI/CD or Tests

What this PR does / why we need it:

In APISIX Standalone mode, an ADC command is launched for each endpoint to perform synchronization. For Node.js, this approach incurs significant startup overhead, and the cost grows linearly with the number of endpoints, leading to considerable resource consumption.

To address this issue, we introduce the ADC Server mode, which runs as a persistent service to reuse processes and significantly reduce CPU overhead. In addition, ADC provides the capability to update multiple endpoints in Standalone mode, further improving synchronization efficiency and overall performance.

Pre-submission checklist:

• Did you explain what problem does this PR solve? Or what new features have been added?
• Have you added corresponding test cases?
• Have you modified the corresponding document?
• Is this PR backward compatible? If it is not backward compatible, please discuss on the mailing list first