Implement tool to help with `**/*.scss` -> `styleUrls` migration

[imhoffd]

https://github.com/ionic-team/ionic/blob/master/angular/BREAKING.md#theming

Previously all scss files in the src directory were imported. Now each scss file should be included for the component via Angular's styleUrls metadata.

*.scss files next to pages we can assume can be automatically migrated, which means the following:

• Remove root page-* selector
• If Sass exists outside the selector, warn about it because we can't/shouldn't migrate it
• Add the relative file path to the scss file to styleUrls of the page component metadata

[imhoffd]

Would this be possible using TSLint replacements? cc @cwoolum

[cwoolum]

There is a CSS AST Parser and Lexer in Codelyzer so that should work. See https://github.com/mgechev/codelyzer/blob/master/src/noUnusedCssRule.ts for an example of the CSS Tree being walked. They use https://github.com/chrisdickinson/cssauron to parse the CSS

[j3gb3rt]

Would it make more since to have this be a cli script. I think doing this through a JS / TS directly would be much easier and be ok since it's a one time run

[cwoolum]

I'd like to remain consistent on our approach with this project.

[kodeine]

So is this feature coming in or not?

[cwoolum]

I have not figured out a way to do this but if you figure it out and would like to submit a PR, we would be happy to look at it!