LPS-44291 CKEditor styles are inverted in RTL langauges

Hey Nate,

We've found that the css files of the ckeditor have their own logic to mirror styles for RTL languages. Thus, they shouldn't be processed by our new RTL logic to prevent a "double-mirroring".

These changes allow defining paths that should be excluded from the RTL generation and set the files under the ckeditor folder by default. If you're ok with it, please resend this pull to @brianchandotcom for Java revision.

Thanks!!

@jbalsas