[Suggestion] Add support for different upstream proxy connection formats

[reporter29]

I've been using HTTP Toolkit quite frequently with HTTP/Socks5 proxies, and my proxy provider provides the proxies in the following format: host:port:user:pass. This format is currently unsupported which makes it a nuance as I have to adjust the format manually every time I switch proxies.

Various proxy sites format the proxies differently, but the majority of them follow the conventions below:

• host:port:user:pass
• host:port@user:pass
• user:pass:host:port
• user:pass@host:port (supported)
• host:port (supported)

Can support for the unsupported formats (the first three) be added?

[reporter29]

Based on this code, it looks like whatever library we're using expects the proxy to be in the currently supported two formats. It should be simple enough to update the connection card to support these formats in the validation and translate it to the user:pass@host:port format if authentication is provided.