This adds the primary reactions to the action bar. They act as toggles where you
can only select one from each group at a time.
Note that currently we aren't actually sending the reaction at all. That's left
for a separate task.
Fixes https://github.com/vector-im/riot-web/issues/9576
This applies the new design for multiple buttons in the message action bar,
paving the way for more things to appear here.
In addition, this changes the existing options button to use the three vertical
dots icon. Some theme colors are also tweaked to align with what they were meant
to be from the unified palette.
This adds a new action bar component to hold multiple per-message actions. This
existing options button has moved to this new component, and is currently the
only action.
