build.cmds: Move build.App.cmd_xxx() here

For every cmd_xxx() method in build.App, create a class that's
instatiated for running the respective command. This has the
advantage of making App.py smaller (and faster), and having smaller,
more maintainable command modules adhering to a common interface.

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

src/python/jw/build/cmds/CmdPath.py

@@ -0,0 +1,25 @@
+# -*- coding: utf-8 -*-
+
+from argparse import Namespace, ArgumentParser
+
+from ..Cmd import Cmd
+
+class CmdPath(Cmd): # export
+
+    def __init__(self) -> None:
+        super().__init__('path', help='path')
+
+    def add_arguments(self, parser: ArgumentParser) -> None:
+        super().add_arguments(parser)
+        parser.add_argument('module', nargs='*', help='Modules')
+
+    def _run(self, args: Namespace) -> None:
+        deps = self.app.get_modules_from_project_txt(args.module, ['pkg.requires.jw'], 'run',
+                scope = 2, add_self=True, names_only=True)
+        r = ''
+        for m in deps:
+            pd = self.app.proj_dir(m)
+            if pd is None:
+                continue
+            r = r + ':' + pd + '/bin'
+        print(r[1:])