Add new InfoBar control / Improve styles for InfoBarMessageControl

[GeertvanHorrik]

The default style for the info bar message control looks a bit outdated. We don't want to make changes in Catel, but want to restyle it in Orc.Theming.

Current look:

We also want a similar control to be introduced where we can add custom content. So this means we want to:

1. Introduce new control (InfoBar)
2. (re)style the InfoBarMessageControl (which is only used for validation issues) with a similar look and feel

I am not sure whether we should put this into Orc.Theming or Orc.Controls. What are your thoughts @ceo1647 ?

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.