`busway=opposite_lane` not interpreted correctly

[westnordost]

It looks like some busway=opposite_lane tagging is not interpreted correctly.

The table below assumes a country with right-hand traffic. Note that the sides flip if oneway=-1 and if it is in a country with left-hand traffic.

input	current output	expected output
``` oneway=yes busway=opposite_lane ```	``` oneway=yes lanes=1 busway:both=lane ```	```diff oneway=yes - lanes=1 - busway:both=lane + busway:left=lane ```
``` oneway=-1 busway=opposite_lane ```	``` lanes=2 ```	```diff - lanes=2 + oneway=-1 + busway:right=lane ```