Enhancement: Simplify people sharing sidebar  

We have reworked the people sharing sidebar to not be split into 
show/edit/create panels. The create form now is fixed to the top 
with the sharees list below and editing happening in-line.

https://github.com/owncloud/web/pull/6039
https://github.com/owncloud/web/issues/5923
https://github.com/owncloud/web/issues/5608
https://github.com/owncloud/web/issues/5797
