Issue #3186304 by idebr, bgilhome, lobsterr, jcnventura: Add configuration...

Issue #3186304 by idebr, bgilhome, lobsterr, jcnventura: Add configuration schema for Single Date Time Picker field widgets

config/schema/single_datetime.schema.yml

+field.widget.settings.single_date_time_widget:
+  type: mapping
+  label: 'Single DateTime Picker Settings'
+  mapping:
+    hour_format:
+      type: string
+    allow_seconds:
+      type: boolean
+    allow_times:
+      type: string
+    allowed_hours:
+      type: string
+    disable_days:
+      type: sequence
+      sequence:
+        type: integer
+    exclude_date:
+      type: string
+    inline:
+      type: boolean
+    mask:
+      type: boolean
+    datetimepicker_theme:
+      type: string
+    start_date:
+      type: string
+    min_date:
+      type: string
+    max_date:
+      type: string
+    year_start:
+      type: string
+    year_end:
+      type: string
+    allow_blank:
+      type: boolean
+
+field.widget.settings.single_date_time_range_widget:
+  type: field.widget.settings.single_date_time_widget