[Feature]: Improve `UntuplePass`

[nicolaassolini-qntm]

Problem Statement

When compiling programs as

from guppylang import guppy
from guppylang.std.collections import Stack
from guppylang.std.builtins import array

@guppy.struct
class MyStruct:
    qb: array[int, 1]
    stack: Stack[int, 1]

@guppy.declare
def state_gen() -> MyStruct: ...

@guppy.declare
def state_discard(s: MyStruct @ owned) -> None: ...

@guppy
def wrapper() -> None:
    state = state_gen()
    state_discard(state)

we do not fully simplify the hugr.
UntuplePass only removes MakeTuple -> UnpackTuple sequence. Also, the pass is not iterative, so MakeTuple -> MakeTuple -> Unpack -> Unpack only removes the internal pair.