Add toolbars to Qt plotter

[banesullivan]

What other options should be in a toolbar?

Perhaps we should overhaul the saved camera locations to be managed in a toolbar?

[banesullivan]

I've generalized this so that we could add various toolbars

[codecov-io]

Codecov Report

Merging #351 into master will increase coverage by 0.02%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #351      +/-   ##
==========================================
+ Coverage   84.62%   84.65%   +0.02%     
==========================================
  Files          30       30              
  Lines        7169     7181      +12     
==========================================
+ Hits         6067     6079      +12     
  Misses       1102     1102

[akaszynski]

Saved locations might look great as a table within a panel, but that’s quite an overhaul. I like the toolbar.

[banesullivan]

It was pretty easy to reimplement the saved cameras into a toolbar:

[banesullivan]

I'm getting some weird warning when I try to move the toolbar:

qt.qpa.cocoa.window: <QNSPanel: 0x7ff69c8ecce0> has active key-value observers (KVO)! 
These will stop working now that the window is recreated, and will result in exceptions when the
observers are removed. Break in QCocoaWindow::recreateWindowIfNeeded to debug.

Also the window moves when relocate one of the toolbars

[banesullivan]

@GuillaumeFavelier, you leverage the BackgrounPlotter a lot, are there any other features you'd like to see as a toolbar?

Also, if you have the time, a code review would be much appreciated since you have more experience with Qt than I.