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.
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
Connor Shea