Add Configuration Option for Network Proxy in Copilot CLI #134

Currently, Copilot CLI does not provide a built-in way for users to configure network proxy settings, which can be problematic in environments requiring proxy access for internet connectivity. Introducing a configurable proxy option, such as through command-line flags or a configuration file, would allow users to specify proxy details (e.g., host, port, authentication) seamlessly. This enhancement would improve usability in corporate or restricted network setups, enabling smoother integration and reducing manual workarounds. Implementation could follow standard CLI patterns, like adding --proxy flags or a proxy section in a config file.