Customizer: Avoid losing focus when adding widgets via keyboard.

props sathishn.
fixes #28835.
Built from https://develop.svn.wordpress.org/trunk@29237


git-svn-id: http://core.svn.wordpress.org/trunk@29021 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Customizer: Add widget title to Move/Up/Down controls to provide context for screen readers when reordering or moving widgets.

fixes #28889.
Built from https://develop.svn.wordpress.org/trunk@29238


git-svn-id: http://core.svn.wordpress.org/trunk@29022 1a063a9b-81f0-0310-95a4-ce76da25c4cd