Use new proxy_enable and proxy_url settings

[link2xt]

With core release 1.143.0 old socks5_* settings are deprecated and proxy_* should be used instead.

This should be done when done is updated from 1.142.x.

deltachat/deltachat-android#3292 gives an idea how the screen looks like in Android

Step 1

• Change Setting Types: socks5_enabled, socks5_host, socks5_port, socks5_user, socks5_password => proxy_enabled, proxy_url
• Adapt form: One text field for one proxy_url (placeholder: "Enter proxy URL here"
• UI: Show explaining text: "Supported proxy types: HTTP(S), SOCKS5 and Shadowsocks"

Step 2 (in separate PR)

• UI: add client side validation
• UI: Show connectivity status & proxy type
• UI: enable multiple proxy url entries
• if a proxy is clicked/selected/added, enable "use proxy" toggle

Step 3 (in separate PR)

• Proxy UI should also be moved out of configuration and into a separate screen like done on Android: Add separate view for proxy settings deltachat-android#3277

Sharing is probably not necessary on desktop

[nicodh]

@link2xt : do we not support username & password for proxies anymore or can it be entered in the form username:[email protected]:8080

[link2xt]

Username and password are supported in the form of socks5://username:password@host:port.
Username and password should be URL-encoded.

[Simon-Laux]

isn't there also a new qr code type desktop should support?

deltachat/interface#75
deltachat/deltachat-core-rust#5895

[r10s]

yip, there is DC_QR_PROXY, which should be passed to dc_set_config_from_qr() after confirmation, using proxy_use_proxy_confirm.

it supports not only SOCKS5 but also other proxies meanwhile, iirc