Maintains physical table's schema

[waynexia]

What type of enhancement is this?

User experience

What does the enhancement do?

Maintain the physical table's schema to make it queryable.

• Extend the region server's interface. Make it possible to return an extra customized map feat: add extension field to region response greptime-proto#138
• Return physical schema's change in metric engine feat: return new added columns in region server's extension response #3533
• Receive and process physical schema's change in meta server

Implementation challenges

No response