feat: add support for setting resolve timeout

[nicklasl]

Add timeout support to Confidence SDK

This PR adds timeout configuration and improved error handling to the Confidence Python SDK:

Changes

• Add configurable timeout for network requests (default: 10 seconds)
• Properly handle request timeouts with descriptive error messages
• Return default values with appropriate error codes when timeouts occur
• Improve error handling in flag resolution methods
• Add TIMEOUT to error codes and reasons
• Update documentation with timeout configuration examples

Benefits

• Better reliability in high-latency environments
• More predictable behavior when network issues occur
• Improved developer experience with clear error messages
• Enhanced control over SDK behavior in production environments
• This change allows developers to configure shorter timeouts when needed, ensuring applications remain responsive even when the flag resolution service is experiencing delays.