Raise error if setting ignored input

[ElliottKasoar]

Related to aiidateam/aiida-workgraph#486, if you manually set an input for a task that is linked to a graph input or previous task, it will be "set", but unused. For example:

from aiida import load_profile
from aiida_workgraph import task

load_profile()

@task
def add(x, y):
    return x + y

@task
def multiply(x, y):
    return x * y

from aiida_workgraph import WorkGraph, spec
from typing import Any

with WorkGraph('AddMultiplyContextManager', inputs=spec.namespace(x=Any, y=Any, z=Any)) as wg:
    the_sum = add(
        x=wg.inputs.x,
        y=wg.inputs.y,
    ).result

    the_product = multiply(
        x=the_sum,
        y=wg.inputs.z,
    ).result

    wg.outputs.result = the_product

wg.inputs = {"x": 2, "y": 3, "z": 4}
wg.tasks.multiply.inputs.y = 6

wg.run()

print(wg.tasks.add.inputs.x)
print(wg.tasks.add.inputs.y)
print(wg.tasks.multiply.inputs.x)
print(wg.tasks.multiply.inputs.y)
print(wg.outputs.result.value)

This returns

SocketAny(name='x', value=None)
SocketAny(name='y', value=None)
SocketAny(name='x', value=None)
SocketAny(name='y', value=6)
uuid: 07f3c705-b112-4fba-97fe-155c2a14b763 (pk: 29100) value: 20

This should raise an error, as discussed with @superstar54, as the y input is not actually used.

It would also be nice if we could somehow see something more akin to print(wg.tasks.add.inputs.x._links) when viewing the values that are None, but this is probably a different issue.