App.distro_xxx: Move properties to Distro.xxx

Commit a19679fec reverted the first attempt to make AsyncSSH reuse
one connection during an instance lifetime. That failed because a lot
of distribution-specific properties were filled in a new event loop
thread started by AsyncRunner, and AsyncSSH didn't like that.

This commit is the first part of the solution: Move those properties
from the App class to the Distro class, and load the Distro class
in an async loader. As soon as it's instantiated, it can provide all
its properties without cluttering the code with async keywords.

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

src/python/jw/pkg/cmds/distro/CmdInstall.py

@@ -15,8 +15,8 @@ class CmdInstall(Cmd): # export
         parser.add_argument("names", nargs="*", help="Packages to be installed")
         parser.add_argument('--only-update', default=False, action='store_true', help='Only update the listed packages, don\'t install them')
         parser.add_argument('-F', '--fixed-strings', action='store_true',
-                            help='Don\'t expand platform info macros in <names>')
+                            help='Don\'t expand platform.expand_macros macros in <names>')
 
     async def _run(self, args: Namespace) -> None:
-        names = names if args.fixed_strings else self.app.distro_info(args.names)
+        names = names if args.fixed_strings else self.app.distro.expand_macros(args.names)
         return await self.distro.install(names, only_update=args.only_update)