pyproject.toml: Enforce import annotations style

Add new ruff rules and fix their fallout:
future-annotations = true
   select = [
    "TC",  # type-checking import placement rules
    "FA",  # future annotations rules
   ]
This comprises:
- Streamline imports and exports in cmds.xxx.Cmd
    - Import base class as "Base"
    - Export types Cmd and Parent via __all__
- Move all types imported only for annotation below TYPE_CHECKING
- Use "from __future__ import annotations" all over the place
Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/pkg/lib/TarIo.py

@@ -6,10 +6,13 @@ import tarfile
 
 from tarfile import TarFile, TarInfo
 
-from .base import StatResult
 from .CopyContext import CopyContext
 from .ExecContext import ExecContext
 from .log import DEBUG, ERR, log
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from .base import StatResult
 
 class TarIo(CopyContext):