Implement a framework for having common code for release scripts (#55893)

* Implement a framework for having common code for release scripts

* Release scripts will go through hacking/build-ansible.  build-ansible is
  a pluggable script which will set a directory that has common code for
  non-enduser scripts.  It will then invoke the plugin which implements
  that subcommand.  Uses straight.plugin for loading each sub-command.

* We're going to add tools which are needed to test ansible (the changelog
  generation, for instance) so we need to include the pieces relevant to
  that in the tarball.

* Add straight.plugin to the sanity test requirements for the same
  reason

* Skip compile test just for build-ansible plugins which won't be run as
  part of sanity tests.

hacking/build-ansible

@@ -0,0 +1,76 @@
+#!/usr/bin/env python3
+# coding: utf-8
+# PYTHON_ARGCOMPLETE_OK
+# Copyright: (c) 2019, Ansible Project
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+
+# Make coding more python3-ish
+from __future__ import (absolute_import, division, print_function)
+__metaclass__ = type
+
+
+import argparse
+import os.path
+import sys
+
+from straight.plugin import load
+
+try:
+    import argcomplete
+except ImportError:
+    argcomplete = None
+
+
+def set_sys_path(this_script=__file__):
+    """Add path to the common librarydirectory to :attr:`sys.path`"""
+    hacking_dir = os.path.dirname(this_script)
+    libdir = os.path.abspath(os.path.join(hacking_dir, 'build_library'))
+
+    if libdir not in sys.path:
+        sys.path.insert(0, libdir)
+
+
+set_sys_path()
+
+from build_ansible import commands
+
+
+def create_arg_parser(program_name):
+    """
+    Creates a command line argument parser
+
+    :arg program_name: The name of the script.  Used in help texts
+    """
+    parser = argparse.ArgumentParser(prog=program_name,
+                                     description="Implements utilities to build Ansible")
+    return parser
+
+
+def main():
+    """
+    Main entrypoint of the script
+
+    "It all starts here"
+    """
+    subcommands = load('build_ansible.command_plugins', subclasses=commands.Command)
+
+    arg_parser = create_arg_parser(os.path.basename(sys.argv[0]))
+    subparsers = arg_parser.add_subparsers(title='Subcommands', dest='command',
+                                           help='for help use build-ansible SUBCOMMANDS -h')
+    subcommands.pipe('init_parser', subparsers.add_parser)
+
+    if argcomplete:
+        argcomplete.autocomplete(arg_parser)
+
+    args = arg_parser.parse_args(sys.argv[1:])
+
+    for subcommand in subcommands:
+        if subcommand.name == args.command:
+            sys.exit(subcommand.main(args))
+
+    print('Error: Select a subcommand')
+    arg_parser.print_usage()
+
+
+if __name__ == '__main__':
+    main()