opacity_state_to_numba -> to_numba and moved to as a method of class …

…OpacityState (#2932)

* for test

* Revert "for test"

This reverts commit 55a190d.

* opacity_state_to_numba -> to_numba and also a method of OpacityState

* Revert "opacity_state_to_numba -> to_numba and also a method of OpacityState"

This reverts commit 65f1a66.

* opacity_state_to_numba -> to_numba and also a method of OpacityState

* Revert "for test"

This reverts commit 55a190d.

* maybe fixes tests failure

* safe initialisation

* using from_plasma

* using from_plasma

* Missing from_plasma usage