Integrate date-picker calendar input auto-focus option and functionality

[cnotv]

What problem does this feature solve?

Allow to optionally automatically focus the date input field on panel open.

This would allow quick editing.

The proposed implementation uses "document.querySelector" which probably you would like to avoid.

What does the proposed API look like?

@Input() @InputBoolean() calInputAutoFocus: boolean;
@ViewChild('datepicker') datepicker: NzDatePickerComponent;

ngOnInit() {
    if (calInputAutoFocus) {
      this.subscribeInputFocus();
    }

}

private subscribeInputFocus(): Subscription {
    return this.datepicker.nzOnOpenChange.subscribe((open: boolean) => {
      if (open) {
        setTimeout(() => {
          const calInput = document.querySelector(
            'calendar-input input.ant-calendar-input'
          ) as HTMLInputElement;
          calInput.focus();
        });
      }
    });
}

[mateobelanger]

This would be great!