[Feature]: Add material icons theme

[jruipinto]

It would be great if we could choose between icon themes. I personally like https://github.com/PKief/vscode-material-icon-theme
Other developpers may have other tastes.
Choosing between some icon themes, instead having only the default, would be great.

[dderevjanik]

Hi @jruipinto,
thank you for creating an issue.

Letting user to change theme on the fly would need major revamp of github-vscode-icons. It isn't impossible, but it could take some time. First, we need to create UI, where can user switch theme.... second, we would need to convert other vsc themes to our format.

Not sure how much time it takes, but its very good idea to support other themes 👍