Add toolbar to configure 3D viewer

[paskino]

Takes from https://github.com/Dagonite/CILViewer/tree/viewer_toolbar into current master

Tested with vtk9 and vtk8

supersedes #337
closes #331

The FormDialog for Volume render settings still is missing the following properties:

• a way to manually change the slider position: swap the QLabel for a QDoubleSpinBox UISliderWidget to have a QDoubleSpinBox attached eqt#125
• Monitor sliderDown in the connection to the signal valueChanged in the slot otherwise the volume render gets triggered too often.
• Add a way to change the maximum opacity

Currently a workaround is in place by setting 2 parameters from CLI for the cilviewer
https://github.com/vais-ral/CILViewer/blob/9287248ccf12f2a8e1e549d9637770aca01ce2e0/Wrappers/Python/ccpi/viewer/standalone_viewer.py#L168-L169

• scale_factor controls how many (?) steps there are in the slider, default is 100. See UISliderWidget
• max_opacity controls the maximum opacity of the volume render opacity transfer function.

[paskino]

Unit tests are missing...

[paskino]

The FormDialog for Volume render settings still is missing:

• a way to manually change the slider position: swap the QLabel for a QDoubleSpinBox UISliderWidget to have a QDoubleSpinBox attached eqt#125
• Monitor sliderDown in the connection to the signal valueChanged in the slot otherwise the volume render gets triggered too often.
• Add a way to change the maximum opacity

[hrobarts]

@lauramurgatroyd showed me how to use the tool bar and it worked really well for this shell dataset from https://doi.org/10.5281/zenodo.6983008