feat(csharp): add statement-level trace parent support

[eric-wang-1990]

Summary

Enable setting trace parent at the statement level for connection pooling scenarios like Power BI, where multiple queries reuse the same connection but need different trace IDs for distributed tracing.

Changes

• TracingStatement: Add _statementTraceParent field and SetTraceParent() method
• TracingStatement: TraceParent property now returns statement override or falls back to connection's trace parent
• HiveServer2Statement: Add SetOption case for AdbcOptions.Telemetry.TraceParent
• Add comprehensive test coverage for statement-level trace parent functionality

Motivation

This brings C# implementation to parity with Go drivers which already support statement-level trace parent via SetOption.

Power BI Use Case

Power BI uses connection pooling where multiple queries reuse the same connection. Each Power BI query has its own trace ID for distributed tracing correlation. Without statement-level trace parent support, all queries from a pooled connection would share the same trace context, making it impossible to correlate individual query traces.

With this change, Power BI can:

var connection = pool.GetConnection();

// Query 1 with Trace ID A
var stmt1 = connection.CreateStatement();
stmt1.SetOption("adbc.telemetry.trace_parent", powerBiQueryTraceIdA);
stmt1.ExecuteQuery();

// Query 2 with Trace ID B (same connection!)
var stmt2 = connection.CreateStatement();
stmt2.SetOption("adbc.telemetry.trace_parent", powerBiQueryTraceIdB);
stmt2.ExecuteQuery();

Test Plan

Added CanSetTraceParentOnStatement test that verifies:

1. Statement inherits connection's trace parent by default
2. Statement can override with its own trace parent via SetOption
3. Activities created by the statement use the statement's trace parent
4. Setting trace parent to null falls back to connection's trace parent

All existing tests pass.

🤖 Generated with Claude Code

[CurtHagenlocher]

Thanks!

[birschick-bq]

I'm think we want to update the trace parent all objects that use the Trace instance. I don't think we want a separate value for the statement.

[birschick-bq]

I'm not convinced we need a separate trace parent for statements.

Because the statement will use the connection to make calls, if the trace parent is not passed to the connection, the connection tracing won't include the trace parent value.

[eric-wang-1990]

This is just for enable databricks to override the traceparent that passed from PBI for statement level.
I am fine with reverting this and use some other generic approach to support, let me know what you think