We don't hide popover on click for formatting buttons, emoji picker and time
picker.
Emoji and time picker popovers need a reference to be displayed,
hence we don't hide them.
Not hiding formatting buttons is based on past discussion.
The current instance of compose popover is stored locally
so that we can access it across different modules.
The basic approach for hiding / displaying a button is based on
width and is executed at `sm` breakpoint as per our
`css_variables.js`.
Used handlebars and `hide/show-sm` css class to make this
work. This avoids using too much JS to hide/display elements.
Aman Agrawal