Implement content apps code config and manifest

src/Umbraco.Core/Models/ContentEditing/IContentAppDefinition.cs

@@ -0,0 +1,20 @@
+namespace Umbraco.Core.Models.ContentEditing
+{
+    /// <summary>
+    /// Represents a content app definition.
+    /// </summary>
+    public interface IContentAppDefinition
+    {
+        /// <summary>
+        /// Gets the content app for an object.
+        /// </summary>
+        /// <param name="source">The source object.</param>
+        /// <returns>The content app for the object, or null.</returns>
+        /// <remarks>
+        /// <para>The definition must determine, based on <paramref name="source"/>, whether
+        /// the content app should be displayed or not, and return either a <see cref="ContentApp"/>
+        /// instance, or null.</para>
+        /// </remarks>
+        ContentApp GetContentAppFor(object source);
+    }
+}