[Apache Arrow Flight] Support Flight SQL Metadata queries

[4ertus2]

For full Arrow Flight SQL support we have to implement CommandGet* methods with DB meta information:
https://arrow.apache.org/docs/format/FlightSql.html#sql-metadata

Some of functions are easy to implement. Others need knowledge of the system.

Related to #126 #127

[SaelKimberly]

Hello, everyone!

Any progress here?)

There is a good examples of big data enterprise OLAP databases, which integrates Arrow Flight SQL in their system, and it is really strong benefit for prefer them over YDB:

• Apache Doris (full Java and C++ ready to use open source implementation, 2021)
• StarRocks (great PR, Aug 2024, open source Java and C++ versions)
• Dremio (open source Java implementation, from beginning of the project)

In this situation, I think, there is a good reason to keep working on this issue, especially because of full internal compatibility of YDB with Apache Arrow...

gRPC is good, yes, but I really don't understand this silence about Arrow Flight in two past years...