Sharing: Add new share

Created by: JosephKiranBabu

Complexity: 3 points

Implement add share functionality for the sharing module.

• Assumption: Plinth application for web sharing is created. #943 (closed)
• Assumption: Authentication happens with SSO module.
• Allow adding a new share. Path of the folder to share is an input and optionally a group to which the access is restricted is also selected.
• This application has to create Apache web server configuration to share a folder on a URL such as /share/<share_name>.
• Sharing may optionally be restricted to a particular user group. Sharing may also be for entire public.