core: cleanup deprecations, exclude from type checking and show runtime warnings

among affected things:

- core.common.assert_never
- core.common.cproperty
- core.common.isoparse
- core.common.mcachew
- core.common.the
- core.common.tzdatetime
- core.compat.sqlite_backup

my/location/google.py

@@ -19,8 +19,8 @@ import re
 # pip3 install geopy
 import geopy # type: ignore
 
-from ..core.common import LazyLogger, mcachew
-from ..core.cachew import cache_dir
+from my.core.common import LazyLogger
+from my.core.cachew import cache_dir, mcachew
 
 from my.core.warnings import high