Add option to show only start or end date in the DateTime Range custom formatter

core/modules/datetime_range/config/schema/datetime_range.schema.yml

@@ -31,6 +31,14 @@ field.formatter.settings.daterange_default:
   type: field.formatter.settings.datetime_default
   label: 'Date range default display format settings'
   mapping:
+    from_to:
+      type: string
+      label: 'Display'
+      constraints:
+        Choice:
+          - both
+          - start_date
+          - end_date
     separator:
       type: label
       label: 'Separator'
@@ -40,6 +48,14 @@ field.formatter.settings.daterange_plain:
   type: field.formatter.settings.datetime_plain
   label: 'Date range plain display format settings'
   mapping:
+    from_to:
+      type: string
+      label: 'Display'
+      constraints:
+        Choice:
+          - both
+          - start_date
+          - end_date
     separator:
       type: label
       label: 'Separator'
@@ -49,6 +65,14 @@ field.formatter.settings.daterange_custom:
   type: field.formatter.settings.datetime_custom
   label: 'Date range custom display format settings'
   mapping:
+    from_to:
+      type: string
+      label: 'Display'
+      constraints:
+        Choice:
+          - both
+          - start_date
+          - end_date
     separator:
       type: label
       label: 'Separator'