add the ability to mix text based metadata fields, authority controlled fields and typed items in the same section

src/app/core/shared/metadata-representation/metadata-representation.model.ts

@@ -0,0 +1,31 @@
+/**
+ * An Enum defining the representation type of metadata
+ */
+export enum MetadataRepresentationType {
+  None = 'none',
+  Item = 'item',
+  AuthorityControlled = 'authority_controlled',
+  PlainText = 'plain_text'
+}
+
+/**
+ * An interface containing information about how we should represent certain metadata
+ */
+export interface MetadataRepresentation {
+  /**
+   * The type of item this metadata is representing
+   * e.g. 'Person'
+   * This can be used for template matching
+   */
+  itemType: string;
+
+  /**
+   * How we should render the metadata in a list
+   */
+  representationType: MetadataRepresentationType,
+
+  /**
+   * Fetches the primary value to be displayed
+   */
+  getPrimaryValue(): string
+}