Allow sponsors access to all roles on their units

It has been decided that a sponsor at a unit should have access to all roles at that unit. This includes all units accessible through hierarchical access.

Resolves: GREG-150

greg/migrations/0019_add_ou_parent_relatedname.py

+# Generated by Django 3.2.9 on 2021-12-03 08:01
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("greg", "0018_alter_identity_type"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="organizationalunit",
+            name="parent",
+            field=models.ForeignKey(
+                blank=True,
+                null=True,
+                on_delete=django.db.models.deletion.PROTECT,
+                related_name="children",
+                to="greg.organizationalunit",
+            ),
+        ),
+    ]