www/py-dj50-django-tree-queries: New port

Query Django model trees using adjacency lists and recursive common
table expressions.

Supports PostgreSQL, sqlite3 (3.8.3 or higher) and MariaDB (10.2.2 or
higher) and MySQL (8.0 or higher, if running without
ONLY_FULL_GROUP_BY).

MFH: 2025Q1 (needed by www/py-dj50-strawberry-graphql-django)
(cherry picked from commit 26a27d4727b5df8cb70df5fdc60903746d482592)