BHV-8467: moon.ScrollStrategy update and clean-up.

Issue
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When moving in 5-way mode in a `moon.Scroller` that has `spotlightPagingControls:false` and then changing to pointer mode, the paging controls are no longer spottable.

Fix
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Reworked the logic for `moon.ScrollStrategy`, getting rid of some cruft.

The logic I tried to enforce (as a sanity check for the reviewer):
- The paging controls should always be enabled (as necessary) when scrolling the list in both 5-way and pointer mode. This involved removing a call to `enableDisablePagingControls` from the `enter` handler (as this method would only ever potentially disable the paging controls), and removing the `scrollMathScroll` handler as it doesn't seem like a use case that the scroller would be scrolled without the pointer hovered over the scroller.
- The paging controls should not be visible when the scroller and/or its contents are not spotted. This involved adding a call to `showHideScrollColumns` in the `spotlightModeChanged` handler and removing the call to `enableDisablePagingControls`. This effectively removed the need for the `enableDisablePagingControls` and `hidePagingControls` methods, which were removed entirely as a result. There is an issue where this logic is not enforced when leaving the scroller via 5-way and will be addressed by BHV-9960.
- The paging controls should be hoverable whenever we are focused on the scroller in pointer mode, so a call to `updateHoverOnPagingControls` in the `enter` handler has been added to guarantee this.

Also fixed a prior typo.

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>