Only react to NSView frame changes if VTK itself created the NSView

Without this, VTK will change the size of the NSWindow, which apps
that create their own NSView and NSWindow and merely use VTK to draw into
them might not want/expect.

Fixes a regression I added in I3eb86e9982caae464fffe1c8cfc19035a194ec27
related to bug #14266.

Also added a public getter for the ViewCreated flag.
Also use getters in PrintSelf, since everything there was done getters.

Change-Id: I13ede32d361f9b17e11b8b0b37ad1997a864bf40
Merge topic 'NSView-observation-fix' into master

fca2fd59 Only react to NSView frame changes if VTK itself created the NSView