Show name for named router outles

[rajinder-yadav]

For a named router outlet display its name in the Component Tree.

Picture below has two router outlets, the one at the bottom is named, would be good to display the name inside round brackets like we do for DOM nodes.

[stevenkampen]

@tyllrb I think this one needs to go after #647, which addresses how or IF we should do this. The router outlet name is available in the properties tab when you select the component, so the user can see it. At any rate, this feature, if it goes ahead, will actually be a generic feature applying to potentially any element type and any piece of data within it's instance providers.