Add Default field in the Form Control Component

[Omar-Abdullah-Shaikh-Al-Zoor]

Adding a Default value field in the Form Control

This would be highly useful for the 'Select' and Date fields.
For Date field it could support the 'Today' default value and the other built-in defaults in frappe/erpnext

When loading the page, the default value should set both the component input's value and the model value if any it is set