Replace LESS processing package

[dsevillamartin]

As I was going to replace components/font-awesome with the official fortawesome/font-awesome package to update to FA 6, I came across the following:

ParseError: Unexpected input in _sizing.less on line 15, column 5
13| 
14| // step-based scale (with alignment)
15| each(.fa-sizes(), {
16|   .@{fa-css-prefix}-@{key} {
17|     .fa-size(@value);
18|   }

The wikimedia/less.php package had its last release on Dec 2020. There are issues open for updating to Less.js 3/4 and closed ones that refer to that regarding this issue with each (wikimedia/less.php#49).

It does not look like they are actively maintaining it (just closing PRs, as they stated in some comment) so we may have to replace the package with another.

[dsevillamartin]

All LESS PHP processors are outdated. What we eventually want to do is most likely move to SCSS (e.g. scssphp/scssphp had an update last month).