revert six picto svg changes due to documentation not working (#337)

moved svgs from scss file to assets (should improve chunk size) currently picto-entry.js is 500kb big.
fix tests
rollback to old status

Author: stefan-laux

docs/changelog.md

@@ -52,7 +52,6 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 - **⚠️Breaking**: `six-file-upload` on upload success now returns a `FileList` regardless of the
   value of the `multiple` property
-- Moved `six-picto` SVG's from SCSS file to assets folder to minimize chunk size.
 - Upgraded Stencil to latest release and upgraded Vue output target
 - Upgraded React output target to version 1.0.0