Add support for proxy and dont verify certificate args

[SwiftExtender]

Sometimes archive.org cant be accessed without proxy so i added support for proxy specifying
CLI Example:
waybackpack url --proxy http://host:port -d output_folder

Also i added support for dont verifiying certs. It can be helpful is CA of archive.org cant be trusted (in rare cases it can be fired by using proxies)
CLI Example:
waybackpack url --proxy http://host:port --no-verify-certificate -d output_folder

[jsvine]

Since waybackpack relies on the requests module for fetching archived pages, I believe setting the HTTP{S}_PROXY environment variables should work here, without any need for modifying the code:

... but does that not work for your use case? If so, could you include a test that helps verify/debug?

[SwiftExtender]

Setting PROXY env variables override proxy settings for programs written on Python, Ruby, Go. I would like to set different proxies for different processes

[jsvine]

If I'm understanding your concern correctly, you can also set environment variables on a process-level, e.g.:

HTTPS_PROXY="https://example.com" waybackpack [...]

... which would set the environment variable just for that invocation and not affect any other processes.

[SwiftExtender]

Ok, option for setting proxy may be not useful, but setting disable of certificate check still important