fs/data: move repo related utils to dvc

This moves get_fs_config/get_fs_cloud and ODBManager to DVC
as they require DVC related utilities, and we don't need them
strictly in dvc-objects/dvc-data.
This also adds support to ReferenceHashFile to load from
any filesystem, using it's module name and filename.
Now we can get rid of DVCFileSystem dependency in
ReferenceHashFile.
This is a temporary solution, we really need a registry.
(I am not quite sure if this works in pyinstaller mode,
but I think it should, it's how fsspec does it if I understand
correctly.)

tests/func/test_odb.py

@@ -5,9 +5,9 @@ import configobj
 import pytest
 
 from dvc.cli import main
-from dvc.data.db import ODBManager
 from dvc.objects.errors import ObjectFormatError
 from dvc.objects.hash_info import HashInfo
+from dvc.odbmgr import ODBManager
 from dvc.utils import relpath