App, .cmds.Cmd: Add .distro property

DistroBase's option --id is now redundant to the new global option
--distro-id in the App class, so remove --id. The only added value
DistroBase then brings to the table is its .distro property, which
can be provided by App just fine at this point, given that App has
all it needs to construct a Distro object, so add .distro to App and
remove the entire DistroBase class.

For convenience, also make App.distro available as a newly added
cmds.Cmd.distro property. This also obviates the need for the
distro-related properties in the .distro.Cmd class, remove all that.

Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/pkg/cmds/Cmd.py

@@ -18,3 +18,13 @@ class Cmd(Base): # export
         # the module path of the calling module itself
         cmds_module = type(self).__module__.replace('Cmd', '').lower()
         self.add_subcommands(LoadTypes([cmds_module], type_name_filter=r'Cmd[^.]'))
+
+    async def _run(self, args):
+        import sys
+        # Missing subcommand
+        self.parser.print_help()
+        sys.exit(1)
+
+    @property
+    def distro(self) -> Distro:
+        return self.app.distro