fix(datetime): display today's date and time when value is an empty string

fixes #29669

Author: brandyscarney

core/src/components/datetime/datetime.tsx

@@ -1234,7 +1234,8 @@ export class Datetime implements ComponentInterface {
   }
 
   private processValue = (value?: string | string[] | null) => {
-    const hasValue = value !== null && value !== undefined && (!Array.isArray(value) || value.length > 0);
+    const hasValue =
+      value !== null && value !== undefined && value != '' && (!Array.isArray(value) || value.length > 0);
     const valueToProcess = hasValue ? parseDate(value) : this.defaultParts;
 
     const { minParts, maxParts, workingParts, el } = this;