pass `blockInfo` to extension methods
pass `blockInfo` to extension methods

Sometimes a single extension method needs to service several different
instances of the same opcode. This can happen with variables or custom
procedures, for example. This change allows the extension method to
inspect the `blockInfo` for instance data, including arbitrary
extension-specific properties if necessary.

LLK/scratch-vm,LLK/scratch-vm,LLK/scratch-vm