Unify various placeholders that suggest to add QtQuick3D import

3D view, material browser, and content library all tell usr to add QtQuick3D module in components view if it is missing, but how they do it differs in all cases. Material browser doesn't have link to add it and other two have different parts of the text for link. Also, link now adds View3D as well, so it's bit misleading.

I suggest:

"To use <viewname>, add the QtQuick3D module and View3D component in the Components view or click here." 

And "here" would be the link in all these cases.