Removes unused variables in NewDiscussionModule view
Adds SkipPermissions option to NewDiscussionModule with GuestUrl param, adds docs, fixes bracing
Allows showing New Discussion button to guests without showing to unprivileged members; renames param 'ShowGuests'
Merge pull request #2039 from vanilla/feature/newdiscussion-skippermission

Add 'ShowGuests' & 'GuestUrl' params to NewDiscussionModule