Add browser traffic scanning feature

[mp3butcher]

not to merge right now..just for review, and testing...

How the feature works:
When browsing through proxy all traffic is sent to OpenVideoDownloader on port 1200 as json and then can be analysed easily to find standard streaming tech in request response (HLS,Dash,partial-content video) then url and request headers are sent to ydl for download...

Check build here: https://github.com/mp3butcher/youtube-dl-gui/releases/latest
(Note: I dl mitmproxy from https://github.com/mp3butcher/mitmproxy for zip convenience but you can check I haven't changed anything).

I added macos build too but haven't test if it works, so feel free to report macos problem here

A typical use case for this feature is when page of the video is dynamically loaded with javascript. But what's interesting is that it passes headers to ydl such as the mandatory referer for cross domain embed videos.

How to use scanner:

1. When scanner activated the first time don't forget to install mitmproxy authority certificate (cf image)
   
2. I recommend to use browser proxy switcher extension such as this extension to easily enable/disable use of proxy while browsing (set it up proxy=localhost and port=15930)
   
3. Browse to a streaming content and let the scanner capture the video