Stardew Valley: Move BaseTest out of __init__.py to comply with future conventions (#4991)

* move everything out of init; fix from imports and some typing errors

* why is there a change in multiserver

* fix some relative shits

worlds/stardew_valley/test/TestRegions.py

@@ -3,7 +3,7 @@ import unittest
 from typing import Set
 
 from BaseClasses import get_seed
-from . import SVTestCase
+from .bases import SVTestCase
 from .options.utils import fill_dataclass_with_default
 from .. import create_content
 from ..options import EntranceRandomization, ExcludeGingerIsland, SkillProgression