Add a UI Slider to change speed of eye

[jccampagne]

Related

• First person camera has zero speed in a zero sized scene #9433
• Make (eye) camera speed configurable #6757

What

• Add a UI slider to change the speed of the eye in the view (for "First Person" and "Orbital").
• Update state_3d.last_eye_interaction when slider is changed, otherwise changing the speed will not work unless the user interacts with the view first.

Caveat:

• The values for default, min and max are hardcoded. I was thinking of using the bounding box of the scene (not sure how yet) to set the default value to 1/10th of the largest dimension.
• Still figuring out how this would relates with Store (eye) camera properties of 3D View in Blueprint #6825

[github-actions]

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