CMB-84: Date Picker: revised date string format, added to open state

Day info is added to the DateTimePicker.
1. Added day info into the date string in closed state 
2. Displayed the date string while the date picker is in open state.
The sample is verified by LGSI SDET member.

`source/DateTimePickerBase.js` should not make assumptions based on how it is being used. We should not be checking or validating based on if a value is a date or a time here. When needed, we create properties and/or methods in this kind that should ultimately be set in a subkind (`DatePicker` or `TimePicker`).

Additionally, I believe using the `template` property is the wrong decision in this instance because this would override any ilib locale formatting - is that what this JIRA calls for? Since we're only concerned with showing the weekday in DatePicker, we are better off modifying likewise.