Material-components-web-components: Allow users to define icon font themselves

[dfreedm]

Users would like to be able to load their own icon font for the Material Icons family.
We need to determine if this should be an opt-in, or require users to load the font themselves always.

[jonmann20]

I've been experimenting using this with a LitElement app. I spent some time trying to do this (and also prevent FOUC). It was far easier to just use SVG. I believe this is similar to how iron-icon worked under the hood. Here is what I came up with:
https://gist.github.com/jonmann20/411f5b8de91536f9bb2561f72cbfe59a

[Yuen92]

Also can you provide a way to remove the dependency to the icon like PolymerElement provides for the font roboto :
window.polymerSkipLoadingFontRoboto = true;

Proposition :
window.mwcSkipLoadingIcon = true;

PolymerElement Reference :

https://github.com/PolymerElements/font-roboto/blob/master/roboto.js

mwc-icon source file to modify :

https://github.com/material-components/material-components-web-components/blob/master/packages/icon/src/mwc-icon-font.ts

What do you think @azakus ?

[JosefJezek]

good solution is here https://github.com/andreasbm/weightless/tree/master/src/lib/icon#-%EF%B8%8F-load-the-icon-font