Bug 34215: Introduce a ToolbarButton Vue component

Bug 34215: Introduce a ToolbarButton Vue component

Our toolbar component is not flexible enough, we cannot:
* have something else than a router-link
* have a link outside of the app (it needs to be a Vue route)

This patch adds a ToolbarButton component that is used for existing
button. But other buttons can be added without being a router-link.

Test plan:
No change in behaviour here! Test the buttons in the 4 existing toolbar
(in the ERM module)

Sponsored-by: BULAC - http://www.bulac.fr/
Signed-off-by: Pedro Amorim <pedro.amorim@ptfs-europe.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>