scripts: add dump_bugs_pickle.py

This prints the contents of a zephyr-bugs-$DATE.pickle file in a
format similar to the output of list_issues.py.

It will be useful to have this in tree so that we can better record
the known issues at the time of a particular zephyr release.

The pickle file itself should be created using the bug snapshot
workflow defined in .github/workflows/bug_snapshot.yaml, which can be
triggered manually from this URL:

https://github.com/zephyrproject-rtos/zephyr/actions/workflows/bug_snapshot.yaml

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>

scripts/dump_bugs_pickle.py

@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+
+# Copyright (c) 2022 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: Apache-2.0
+
+# stdlib
+import argparse
+import pickle
+from pathlib import Path
+from typing import List
+
+# third party
+from github.Issue import Issue
+
+def parse_args() -> argparse.Namespace:
+    parser = argparse.ArgumentParser(
+        formatter_class=argparse.RawDescriptionHelpFormatter)
+
+    parser.add_argument('pickle_file', metavar='PICKLE-FILE', type=Path,
+                        help='pickle file containing list of issues')
+
+    return parser.parse_args()
+
+def issue_has_label(issue: Issue, label: str) -> bool:
+    for lbl in issue.labels:
+        if lbl.name == label:
+            return True
+    return False
+
+def is_open_bug(issue: Issue) -> bool:
+    return (issue.pull_request is None and
+            issue.state == 'open' and
+            issue_has_label(issue, 'bug'))
+
+def get_bugs(args: argparse.Namespace) -> List[Issue]:
+    '''Get the bugs to use for analysis, given command line arguments.'''
+    with open(args.pickle_file, 'rb') as f:
+        return [issue for issue in pickle.load(f) if
+                is_open_bug(issue)]
+
+def main() -> None:
+    args = parse_args()
+    bugs = get_bugs(args)
+    for bug in sorted(bugs, key=lambda bug: bug.number):
+        print(f'- :github:`{bug.number}` - {bug.title}')
+
+if __name__ == '__main__':
+    main()