MIR: Control structures

Let's add support for lambdas, lambda-related instructions, and LOOP_LEFT

• APPLY: ty1 : lambda ( pair ty1 ty2 ) ty3 : A — lambda ty2 ty3 : A !10982 (merged)
• EXEC: ty1 : lambda ty1 ty2 : A — ty2 : A !10984 (merged)
• LAMBDA ty1 ty2 instr: A — lambda ty1 ty2 : A !10961 (merged)
• LAMBDA_REC ty1 ty2 instr: A — lambda ty1 ty2 : A !10961 (merged)
• LOOP_LEFT instr: or ty1 ty2 : A — ty2 : A !10990 (merged)