theme: add page transition animations to preset_a
theme: add page transition animations to preset_a

The pager transition style was inadvertently removed at
some point, so add it back.

https://phabricator.endlessm.com/T14649

endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib