Add keyboard shortcut for collection search: Ctrl+F

Also change name of the "Jump to" action to "Search playlist" and
rename appropriate methods.

Both actions now ensure that relevant dock and widget gets shown upon
firing the shortcut.

Patch by Silver Juurik <silverjuurik@gmail.com>

REVIEW: 102956
FEATURE: 257381
GUI: "Jump to" keyboard shortcut renamed to "Search playlist"
FIXED-IN: 2.5