Implement support for sets and other improvements (#34)

* Add a boolean to define item as part of a set
* Add contextual help in admin
* Introduce support to sets and to item code lookup
Also review the url path for pagination

ram/metadata/migrations/0017_alter_property_private.py

@@ -0,0 +1,20 @@
+# Generated by Django 5.0.4 on 2024-04-20 12:49
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("metadata", "0016_alter_decoderdocument_file"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="property",
+            name="private",
+            field=models.BooleanField(
+                default=False, help_text="Property will be only visible to logged users"
+            ),
+        ),
+    ]