Rename btn-new, btn-create and btn-save to btn-success

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Apply the same spam checks to public snippets (either personal snippets
that are public, or public snippets on public projects) as to issues on
public projects.

Altered specs that click capitalised New Snippet button

Applied review feedback missed in  Changes `.no-comment` `opactiy: 0.5` to `opacity: .5`

Added `.btn-wide-on-xs` and applied to snippet buttons

Rearranged datetime created line

Added `avatar_class` option to `link_to_member` so it can be hidden

Made snippet title font heavier

Added file title  bar

Hidden unneeded info from xs screens

Added visibility icon

Reveal file-actions on xs screens

Added comments icon to snippets list items

Refactored no-comments declaration into framework stylesheet

Final touch ups

Fixed snippets_spec

No longer shows New Snippet button to users who aren't able to create a new snippet in the given context.

Also removes the plus icon from the New Snippet buttons, as they're no longer used in other creation buttons.

Fixes #14595.

This reverts commit 3e991230.

# Conflicts:
#	app/models/project.rb

Closes #14328

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Split out header into shared partial
Used action partials to have unique actions for shared and personal
snippets
changed back to created date in list view
Switched to using existing color classes