Before this commit, fir f/o builder was inconsistently
disabled in some places, while it should work only for lazy declarations
Attempt to use it for non-lazy declarations, without maintaining
invariant, that it would also be used for super classes
led to unpredictable results.
This commit introduces opt-in, and marks all related API to three types
* Propagate error to user
* Fine to use, as it's checked if ir f/o builder is enabled
* Fine to use, as it is definitely a lazy class.
Several cases of missing checks was fixed.
^KT-65707
Pavel Kunyavskiy
9532172a22