feat: replace php migration with django migration

- keep latest legacy version in initial migration file
- move propel schema to api legacy app
- remove legacy upgrade tool

api/libretime_api/legacy/migrations/0013_2_5_15.py

@@ -0,0 +1,30 @@
+from django.db import migrations
+
+from ._migrations import legacy_migration_factory
+
+# SAAS-1071
+# Remove not null constraint from file_id fk in third_party_track_references
+# so that we can create track references for downloads (which won't have a
+# file ID until the task is run and the file is POSTed back to Airtime)
+
+UP = """
+ALTER TABLE third_party_track_references ALTER COLUMN file_id DROP NOT NULL;
+"""
+
+DOWN = """
+ALTER TABLE third_party_track_references ALTER COLUMN file_id SET NOT NULL;
+"""
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("legacy", "0012_2_5_14"),
+    ]
+    operations = [
+        migrations.RunPython(
+            code=legacy_migration_factory(
+                target="2.5.15",
+                sql=UP,
+            )
+        )
+    ]