Add flag to create_collection to skip listCollections pre-check. For example:

>>> client.db.create_collection("name")
Collection(...)
>>> client.db.create_collection("name")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/shane/git/mongo-python-driver/pymongo/database.py", line 378, in create_collection
    raise CollectionInvalid("collection %s already exists" % name)
pymongo.errors.CollectionInvalid: collection name already exists
>>> client.db.create_collection("name", check_exists=False)
Collection(...)

Motivation:

1. spec tests assume that drivers do not call listCollections in the createCollection helper. Our current behavior requires workarounds in the spec runner to ignore the listCollections command.
2. This gives us a path to change the default createCollection behavior (to check_exists=False) in pymongo 5.0.
3. I think we made the wrong decision in PYTHON-1936. We should have introduced this option in 3.x and changed the behavior in 4.0.

Note the name of the flag is TBD, check_exists might end up being the final name but it's only an example.