Remove style.css file from the repository

Problem/Motivation

This is only particularly relevant now that #3196545: Allow compatibility mode for legacy support → allows more than one way to compile the stylesheet.

I understand the benefits of having the css file committed so that it isn't required to run gulp to compile the sass, but...

If I have compiled the theme to use legacy support as #3196545: Allow compatibility mode for legacy support → . If I run composer install again this will overwrite this change and require me to re-compile the sass.

Proposed resolution

The style.css in the css directory is a generated file and as such probably shouldn't be committed to the repository.

Or if we want to provide backwards compatibility we could potentially provide a base style.css (in git) and a style.min.css (not in git) with the library dynamically choosing depending on the presence of any generated compiled styles.

Discuss??