add account preferences model and API endpoints for user settings

backend/authentication/migrations/0003_accountpreference.py

@@ -0,0 +1,26 @@
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('authentication', '0002_toolsheduser_profile_picture'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='AccountPreference',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('key', models.CharField(max_length=255)),
+                ('value', models.JSONField()),
+                ('user', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='preferences',
+                                           to='authentication.toolsheduser')),
+            ],
+            options={
+                'unique_together': {('user', 'key')},
+            },
+        ),
+    ]
+