Consider filtering functionality in `ConstrainedQuadraticModel.iter_constraint_data()`

Currently [`ConstrainedQuadraticModel.iter_constraint_data()`](https://github.com/dwavesystems/dimod/blob/835688330a6979bb6eeab7d21bbc8f845f37acbe/dimod/constrained/constrained.py#L1147) always iterates over every constraint in the model.

We should consider adding some keyword arguments to make that a bit easier when handling constraints in bulk. I am imagining something like
```Python
def iter_constraint_data(sample_like, *, filter_function=None):
if callable(filter_function):
yield from filter(filter_function, self.iter_constraint_data(sample_like))
return

...
```
and/or
```Python
def iter_constraint_data(sample_like, *, labels=None):
...

if labels is None:
labels = self.constraint_labels

for label in labels:
constraint = self.constraint(label)

lhs = constraint.lhs.energy((sample, labels))
rhs = constraint.rhs
sense = constraint.sense
...
```