Add Font Awesome v6 support

[rajkumartreads]

Description

Currently, Buefy supports FontAwesome v4 and v5.
FontAwesome v6.0.0 was released on Feb 7, 2022.

FontAwesome v6 overview [A few points from documentation]

Style	Availability	Style class	@font-face weight
Solid	Free Plan	fa-solid	900
Regular	Pro Plans only	fa-regular	400
Light	Pro Plans only	fa-light	300
Thin	Pro Plans only	fa-thin	100
Duotone	Pro Plans only	fa-duotone	900
Brands	Free Plan	fa-brands	400

Aliases

But we wanted to make sure not to break your existing code, so we made aliases for renamed icons to allow them to work with either the old or new names.

And you can use the old or new name for styles as well. So you can still use fas, far, fal, fad, fab, and have fat be the new Thin!

Why Buefy need this feature

Adding official support to FontAwesome v6 would help new projects to adopt Buefy with ease.
Moreover, FontAwesome 6 contains 7000+ new icons with new style options.

[CobraClutch]

It seems like the sizing is wonky on buttons and inputs when using SVG+JS method. See pen here:
https://codepen.io/cobraclutch/pen/jOaKEmG

I think it has something to do with this CSS that is part of Buefy/Bulma:

.icon svg {
width: auto;
height: auto;
}

[fracz]

Ran into the same issue and even prepared a code sandbox before I saw this (closed??) issue. It may help, maybe.

https://codesandbox.io/s/buefy-sidebar-forked-x3yv38?file=/src/App.vue

Consider reopening this issue.

[TheEvilCoder42]

Same issue, I solved it (temporarily) by setting the respective sass variables:

$icon-svg-width: 1rem
$icon-svg-height: 1rem

(Or em if that better suits you)

[scheinercc]

Related to this? FortAwesome/Font-Awesome#18663 (comment)