Include the .pcss extension for PostCSS files

[opdavies]

This PR adds support for the .pcss file extension for PostCSS files.

I've got this to work by overriding the CSS Loader test within my webpack.config.js using the .configureLoaderRule() as documented in https://www.oliverdavies.uk/articles/using-the-pcss-extension-with-webpack-encore.

But it would be nice to have this supported by default to make things simpler and not having to see the Be careful when using Encore.configureLoaderRule() message on each build.

[opdavies]

@weaverryan Any advice on this? The tests are passing here, but failing locally if I run npm run test and don't update the versioned filenames.

1) Functional tests using webpack
   Basic scenarios.
     copyFiles() allows to copy files and folders
       Copy with versioning enabled:

  Uncaught AssertionError: expected '/Users/opdavies/Code/tmp/webpack-encore/test_tmp/oil16n/www/build' to have the same files as [ Array(6) ]
  + expected - actual

   [
     "entrypoints.json"
  -  "main.88a14d18.js"
  +  "main.ceeddab6.js"
     "manifest.json"
  -  "runtime.0c796a0d.js"
  +  "runtime.d2591ff7.js"
     "symfony_logo.ea1ca6f7.png"
     "symfony_logo_alt.f27119c2.png"
   ]

[Lyrkan]

The tests are passing here, but failing locally if I run npm run test and don't update the versioned filenames.

Did you retrieve the dependencies using npm instead of Yarn?
The project only has a yarn.lock file, so if you don't install them through Yarn you won't get the right versions.

[opdavies]

Possibly. :)

I'll delete node_modules, re-download using Yarn and re-try.

[opdavies]

I've re-installed with Yarn and run yarn run test instead, and everything passes.

Thanks @Lyrkan!

[weaverryan]

Thank you @opdavies!