field_to_schema should handle ListField like ListSerializer

[tuky]

Checklist

• I have verified that that issue exists against the master branch of Django REST framework.
• I have searched for similar issues in both open and closed tickets and cannot find a duplicate.
• This is not a usage question. (Those should be directed to the discussion group instead.)
• This cannot be dealt with as a third party library. (We prefer new functionality to be in the form of third party libraries where possible.)
• I have reduced the issue to the simplest possible case.
• I have included a failing test as a pull request. (If you are unable to do so we can still accept the issue.)

Steps to reproduce

from rest_framework.serializers import *
from rest_framework.schemas import *
field_to_schema(ListField(child=CharField()))
field_to_schema(ListSerializer(child=CharField()))

Expected behavior

# output: <coreschema.schemas.Array object at 0x7fc81a0540d0>
# output: <coreschema.schemas.Array object at 0x7fc819b47cd0>

Actual behavior

# output: <coreschema.schemas.String object at 0x7fc81a0540d0>
# output: <coreschema.schemas.Array object at 0x7fc819b47cd0>

https://github.com/encode/django-rest-framework/blob/master/rest_framework/schemas.py#L33

[carltongibson]

Closed by #5326