Add support for shortcuts with the shift key.

Now shortcuts with the shift key can be defined in
frameworks/base/packages/SettingsProvider/res/xml/bookmarks.xml.

Sample:

<bookmark
    package="package"
    class="package.Class"
    shift="true"
    shortcut="z"  />

Bug 26540880

Change-Id: Ib6d6ea59124226d4e4eb8ec9972059f2d71bd77e
(cherry picked from commit e7319ecbbe865db8884914ceb10f526f4e160a64)