Blender Git Loki

VSE: Add tooltips for add_effect_strips operator

This patch adds propper tooltips to the effect strips in the "Add" menu.
Note that not all effect strips are actually in the "Effect Strips"
submenu like color strips, text strips or transitions. For these types
of effect strips, a dediacted tooltip is especially useful.

Reviewed By: ISS

Differential Revision: https://developer.blender.org/D11714