Decompiler3: Bridge the new block system over to the core decompilation code

[ds84182]

The new block system properly finds all Lua block constructs (including CLOSE, needed for finding standalone do end blocks), but the decompilation core doesn't use it. It needs to be modified to switch between the old logic (for comparison) and the new logic (for accuracy).

This is technically a bug because Decompiler3 has some bugs in the current block handling code.