[Feature Request] Either remove the "Playback" tab, or move the controls to a "render" tab (see Issue#1339)

[raindropsfromsky]

Is your feature request related to a problem? Please describe.
The Playback tab is not needed at all.
Its presence only disturbs the workflow.

Describe the solution you'd like
All playback controls are already provided at the bottom of the UI.
The two checkboxes can be added there for completeness' sake.

Instead of having a dedicated tab for playback, these controls can be provided in the Export tab I proposed in issue #1339.
(It makes sense to play back the final product just before exporting.)

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Please also see Issue #1339