It is invalid if the same decoration is applied to the same id multiple
times. This adds a check before adding a decoration that the decoration
is not already in the list. If it is, then the duplicate is not added.
Fixes#3627
SPIR-V disallows bool in interface blocks, which is emulated with uint.
When loading a bool variable (through accessChainLoad()), it's converted
from uint to bool if it came from an interface block.
This was handled for bool and bvecN, but not for bool arrays. This
change implements the conversion for bool arrays.
Closes#2694