System for allowing certain TrainingCategories to be trained by certain levels, regardless of supervisor status

I.e. the haulage department, ref #482. As generic as I can make it I think.

training/migrations/0003_trainingcategory_training_level.py

@@ -0,0 +1,19 @@
+# Generated by Django 3.2.11 on 2022-01-25 12:58
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('training', '0002_alter_traininglevel_options'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='trainingcategory',
+            name='training_level',
+            field=models.ForeignKey(help_text='If this is set, any user with the selected level may pass out users within this category, regardless of other status', null=True, on_delete=django.db.models.deletion.CASCADE, to='training.traininglevel'),
+        ),
+    ]