This change removes constant folding from the Painless user tree. This accomplishes two goals. The first is to remove all optimizations from the user tree which will at a later time become optimization phases for the ir tree. The second is to make the user tree immutable, and this is a step toward that since we will no longer remove/modify/replace nodes in the user tree during the process of constant folding.

One important note is that the conditional promotion code has changed, since the promoteConditional method considered constants (similarly to the JVM spec) that are now removed, but this code path was unreachable to begin with so the constants were never actually used to determine the appropriate promotion.