Add the ability to change the width of the leading space

[JPStrydom]

On some smaller Android devices, the leading space is a bit large, taking up around 20% of the screen.

Currently, we're hiding the leading space and giving horizontal padding to the tabHeaderStyle. This looks okay visually, but makes the scrolling cut off.

Ideally, it'd be nice if we could set a custom width for the leading space.

Is this something that is already possible with some props or styling, or is this something that will need to be added as an enhancement?