jw.build.cmds: Move build.cmds -> cmds.projects

Reorganize the Python module structure. Placing the command classes
under jw.cmds.projects instead of jw.build.cmds will allow to add a
nested command structure, with the current commands, being mostly
related to building software, found below a "projects" toplevel
command.

Other conceivable commands could be "package" for packaging, or
"distro" for commands wrapping the distribution's package manager.

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

src/python/jw/pkg/cmds/projects/CmdRequiredOsPkg.py

@@ -0,0 +1,45 @@
+# -*- coding: utf-8 -*-
+
+from argparse import Namespace, ArgumentParser
+
+from ..Cmd import Cmd
+
+# TODO: seems at least partly redundant to CmdPkgRequires / print_pkg_relations
+class CmdRequiredOsPkg(Cmd): # export
+
+    def __init__(self) -> None:
+        super().__init__('required-os-pkg', help='List distribution packages required for a package')
+
+    def add_arguments(self, parser: ArgumentParser) -> None:
+        super().add_arguments(parser)
+        parser.add_argument('module', nargs='*', help='Modules')
+        parser.add_argument('--flavours', help='Dependency flavours', default='build')
+        parser.add_argument('--skip-excluded', action='store_true', default=False,
+            help='Output empty prerequisite list if module is excluded')
+
+    def _run(self, args: Namespace) -> None:
+        modules = args.module
+        flavours = args.flavours.split()
+        if 'build' in flavours and not 'run' in flavours:
+            # TODO: This adds too much. Only the run dependencies of the build dependencies would be needed.
+            flavours.append('run')
+        self.app.debug("flavours = " + args.flavours)
+        deps = self.app.get_modules_from_project_txt(modules, ['pkg.requires.jw'], flavours,
+                scope = 2, add_self=True, names_only=True)
+        if args.skip_excluded:
+            for d in deps:
+                if self.app.is_excluded_from_build(d) is not None:
+                    deps.remove(d)
+        subsecs = self.app.os_cascade()
+        self.app.debug("subsecs = ", subsecs)
+        requires = []
+        for s in subsecs:
+            for f in flavours:
+                vals = self.app.collect_values(deps, 'pkg.requires.' + s, f)
+                if vals:
+                    requires = requires + vals
+        # TODO: add all not in build tree as -devel
+        r = ''
+        for m in requires:
+            r = r + ' ' + m
+        print(r[1:])