Creates a new, empty emoji picker. An emoji picker is a grid of emoji, each
cell of the grid containing a single emoji. The picker may contain multiple
pages of emoji.
When a user selects an emoji, by either clicking or pressing enter, the
picker fires a goog.ui.Component.EventType.ACTION event with the id. The
client listens on this event and in the handler can retrieve the id of the
selected emoji and do something with it, for instance, inserting an image
tag into a rich text control. An emoji picker does not maintain state. That
is, once an emoji is selected, the emoji picker does not remember which emoji
was selected.
The emoji picker is implemented as a tabpane with each tabpage being a table.
Each of the tables are the same size to prevent jittering when switching
between pages.