Add Go-specific telemetry design document

This design document provides a comprehensive telemetry system design
adapted specifically for the databricks-sql-go driver following Go
best practices and idiomatic patterns.

Key Go-specific adaptations:
- Replaced C# Activity/ActivitySource with context.Context and interceptors
- Used goroutines and channels for async operations
- Applied sync.RWMutex and sync.Once for thread-safe singletons
- Implemented circuit breaker pattern with Go idioms
- Used defer/recover for error handling
- Followed Go naming conventions (unexported types, camelCase)
- Designed around standard library patterns (http.Client, context)
- Included Go-specific testing patterns (unit, integration, benchmarks)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: samikshya-db