Improve visual representation of inline macros, by ensuring
they all use the same CSS attributes and have a reduced vertical padding,
so they don't overlap as much.
We also improved the vertical alignment of the leading icon for these macros.
As a sidefind, we replaced a handcrafted version of the InlineMessage with the
existing InlineMessage component. This also improved alignment of the icon.
This is intended to become a replacement for the angular-based
<opce-macro-wp-quickinfo> component.
However, the new component should be more generic, so that it can
also be used for other cases, such as rich links to wiki pages.