[pixels-server] add query related API.

[bianhq]

• estimate query cost.
• query execution.
• schedule query for the future.

[bianhq]

Detailed todo:

• rename pixels query id to transaction id, and distinguish with the query id in Trino;
• rename lambda.switch to cloud.function.switch and add a session property cloud_function_enabled. This session property takes effect when the switch is set to session;
• merge transaction context into the transaction rpc server;
• support query-id to transaction-id binding in transaction service.
• support query estimation, scheduling, and execution in pixels-server.

[bianhq]

Query estimation to be implemented in a future issue if needed.

[bianhq]

Schedule query for future execution is not needed.