[Feature Request] Add `clampToGround` to polygon options

Now we have both `zIndex` and `clampToGround` options available for `polyline`, but for `polygon`, we only have the `zIndex` option.
Additionally, we cannot use the `zIndex` option on a `polygon` that is not a ground entity.
This behavior is confusing and unintuitive. It is necessary to reach a consensus and make the behavior consistent

Start by comparing the existing clampToGround and zIndex behavior for polylines with the polygon options described in this issue. Determine the intended consistent behavior for ground and non-ground polygons, then verify the result against the relevant polygon and polyline behavior; the issue does not name specific files or tests.

Written by the indexing model from the issue text.