Provide high resolution favicon

[tooomm]

Currently the shields.io favicon is low resolution only.

But current browsers like Firefox use big logo information in their top visites sites section.
There is also no image support for links placed on mobile homescreens (android +ios).

On basically all high resolution screens the operating system has to scale things up so it gets even worse.

[RedSparr0w]

what about something like this:

It's a little different from the original though.

[carlosgub]

Can I create an xml or svg of that, it ok?

[paulmelnikow]

A bunch of work was done on this in #2228, but it wasn't quite completed.

[jaas666]

I can work on this one. In fact I have it ready but I don't know how to test this on my side. I edited the meta.tsx but don't know how to run it on my dev environment.