fix(datetimewidget): fix broken onBlur event handling

[benforshey]

@rsjf (or our onBlur function) did not correctly handle the onBlur event--the input's value would not save to form state. onBlur now calls @rsjf's native onChange event.

fix #53470

[benforshey]

To test this PR, please run mEditor locally and choose any model that uses "format": "date-time" as a property (Alerts do). Using Alerts as an example, verify that (in a new document) you can:

• set a Start with the date picker (click the date you want)
• set an Expiration by either copying/pasting the Start or manually entering the datetime.
• save the document

[KrupaRami]

Everything is working as expected...approving!