feat(search) - add DATETIME FieldType (#4407)

* feat(search) - add DATETIME FieldType

docs/modeling/extending-the-metadata-model.md

@@ -323,7 +323,7 @@ It takes the following parameters:
   annotations. To customize the set of analyzers used to index a certain field, you must add a new field type and define
   the set of mappings to be applied in the MappingsBuilder.
 
-  Thus far, we have implemented 8 fieldTypes:
+  Thus far, we have implemented 9 fieldTypes:
 
     1. *KEYWORD* - Short text fields that only support exact matches, often used only for filtering
 
@@ -342,6 +342,8 @@ It takes the following parameters:
     7. *BOOLEAN* - Boolean fields used for filtering.
 
     8. *COUNT* - Count fields used for filtering.
+  
+    9. *DATETIME* - Datetime fields used to represent timestamps.
 
 - **fieldName**: string (optional) - The name of the field in search index document. Defaults to the field name where
   the annotation resides.

entity-registry/src/main/java/com/linkedin/metadata/models/annotation/SearchableAnnotation.java

@@ -52,7 +52,8 @@ public class SearchableAnnotation {
     URN,
     URN_PARTIAL,
     BOOLEAN,
-    COUNT
+    COUNT,
+    DATETIME
   }
 
   @Nonnull

metadata-io/src/main/java/com/linkedin/metadata/search/elasticsearch/indexbuilder/MappingsBuilder.java

@@ -77,6 +77,8 @@ public class MappingsBuilder {
       mappingForField.put("type", "boolean");
     } else if (fieldType == FieldType.COUNT) {
       mappingForField.put("type", "long");
+    } else if (fieldType == FieldType.DATETIME) {
+      mappingForField.put("type", "date");
     } else {
       log.info("FieldType {} has no mappings implemented", fieldType);
     }