Make %pyproject_buildrequires and %pyproject_save_files argparser errors nicer to macro users

Before:

    %pyproject_buildrequires bogus_arg
    usage: pyproject_buildrequires.py [-h] [-r] [-w] [--wheeldir PATH] [-R]
                                      [-e TOXENVS] [-t] [-x EXTRAS]
                                      [--generate-extras] [-p PYTHON3_PKGVERSION]
                                      [-N]
                                      [requirement_files ...]
    pyproject_buildrequires.py: error: argument requirement_files: can't open 'bogus_arg': ...

    %pyproject_save_files
    ...
    usage: pyproject_save_files.py [-h] --output-files OUTPUT_FILES
                                   --output-modules OUTPUT_MODULES --buildroot
                                   BUILDROOT --sitelib SITELIB --sitearch SITEARCH
                                   --python-version PYTHON_VERSION
                                   --pyproject-record PYPROJECT_RECORD --prefix
                                   PREFIX
                                   varargs [varargs ...]
    pyproject_save_files.py: error: the following arguments are required: varargs

After:

    %pyproject_buildrequires bogus_arg
    usage: %pyproject_buildrequires [-w] [-R] [-e TOXENVS] [-t] [-x EXTRAS] [-N]
                                    [REQUIREMENTS.TXT ...]
    %pyproject_buildrequires: error: argument REQUIREMENTS.TXT: can't open 'bogus_arg': ...

    %pyproject_save_files
    ...
    usage: %pyproject_save_files MODULE_GLOB [MODULE_GLOB ...] [+auto]
    %pyproject_save_files: error: the following arguments are required: MODULE_GLOB

Related: rhbz#2168193

pyproject_buildrequires.py

@@ -424,11 +424,18 @@ def generate_requires(
 
 def main(argv):
     parser = argparse.ArgumentParser(
-        description='Generate BuildRequires for a Python project.'
+        description='Generate BuildRequires for a Python project.',
+        prog='%pyproject_buildrequires',
+        add_help=False,
+    )
+    parser.add_argument(
+        '--help', action='help',
+        default=argparse.SUPPRESS,
+        help=argparse.SUPPRESS,
     )
     parser.add_argument(
         '-r', '--runtime', action='store_true', default=True,
-        help='Generate run-time requirements (default, disable with -R)',
+        help=argparse.SUPPRESS,  # Generate run-time requirements (backwards-compatibility only)
     )
     parser.add_argument(
         '-w', '--wheel', action='store_true', default=False,
@@ -437,7 +444,7 @@ def main(argv):
     )
     parser.add_argument(
         '--wheeldir', metavar='PATH', default=None,
-        help='The directory with wheel, used when -w.',
+        help=argparse.SUPPRESS,
     )
     parser.add_argument(
         '-R', '--no-runtime', action='store_false', dest='runtime',
@@ -460,19 +467,19 @@ def main(argv):
     )
     parser.add_argument(
         '--generate-extras', action='store_true',
-        help='Generate build requirements on Python Extras',
+        help=argparse.SUPPRESS,
     )
     parser.add_argument(
         '-p', '--python3_pkgversion', metavar='PYTHON3_PKGVERSION',
-        default="3", help=('Python version for pythonXdist()'
+        default="3", help=argparse.SUPPRESS,
-                           'or pythonX.Ydist() requirements'),
     )
     parser.add_argument(
         '-N', '--no-use-build-system', dest='use_build_system',
         action='store_false', help='Use -N to indicate that project does not use any build system',
     )
     parser.add_argument(
-       'requirement_files', nargs='*', type=argparse.FileType('r'),
+        'requirement_files', nargs='*', type=argparse.FileType('r'),
+        metavar='REQUIREMENTS.TXT',
         help=('Add buildrequires from file'),
     )
 

pyproject_save_files.py

@@ -742,17 +742,31 @@ def main(cli_args):
 
 
 def argparser():
-    parser = argparse.ArgumentParser()
+    parser = argparse.ArgumentParser(
+        description="Create %{pyproject_files} for a Python project.",
+        prog="%pyproject_save_files",
+        add_help=False,
+        # custom usage to add +auto
+        usage="%(prog)s MODULE_GLOB [MODULE_GLOB ...] [+auto]",
+    )
+    parser.add_argument(
+        '--help', action='help',
+        default=argparse.SUPPRESS,
+        help=argparse.SUPPRESS,
+    )
     r = parser.add_argument_group("required arguments")
-    r.add_argument("--output-files", type=PosixPath, required=True)
+    r.add_argument("--output-files", type=PosixPath, required=True, help=argparse.SUPPRESS)
-    r.add_argument("--output-modules", type=PosixPath, required=True)
+    r.add_argument("--output-modules", type=PosixPath, required=True, help=argparse.SUPPRESS)
-    r.add_argument("--buildroot", type=PosixPath, required=True)
+    r.add_argument("--buildroot", type=PosixPath, required=True, help=argparse.SUPPRESS)
-    r.add_argument("--sitelib", type=BuildrootPath, required=True)
+    r.add_argument("--sitelib", type=BuildrootPath, required=True, help=argparse.SUPPRESS)
-    r.add_argument("--sitearch", type=BuildrootPath, required=True)
+    r.add_argument("--sitearch", type=BuildrootPath, required=True, help=argparse.SUPPRESS)
-    r.add_argument("--python-version", type=str, required=True)
+    r.add_argument("--python-version", type=str, required=True, help=argparse.SUPPRESS)
-    r.add_argument("--pyproject-record", type=PosixPath, required=True)
+    r.add_argument("--pyproject-record", type=PosixPath, required=True, help=argparse.SUPPRESS)
-    r.add_argument("--prefix", type=PosixPath, required=True)
+    r.add_argument("--prefix", type=PosixPath, required=True, help=argparse.SUPPRESS)
-    parser.add_argument("varargs", nargs="+")
+    parser.add_argument(
+        "varargs", nargs="+", metavar="MODULE_GLOB",
+        help="Shell-like glob matching top-level module names to save into %%{pyproject_files}",
+    )
     return parser