Using xvfb-run to expose display via tcp

[diemol]

This will allow another container to attach
itself to the exposed display, and potentially
record the stream.

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Description

This changes slighlty how xvfb is started, and allows exposing the display via tcp.

Motivation and Context

If the display can be accessed via tcp, we can potentially have another container running with ffmpeg and record the display.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have read the contributing document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.