Enhanced Date Range Selection via Dragging

[AmitThakur15]

Description:
Problem:
Currently, the date range selection in the calendar_date_picker2 Flutter package is limited to tapping on individual dates to set the start and end of the range. While this works well for precise selection, it can be cumbersome and time-consuming, especially when selecting a large range of dates.

Feature Request:
I would like to propose adding a new feature that allows users to update or change the date range selection via dragging. This enhancement would enable users to quickly and intuitively adjust the date range by dragging across the calendar view.

Description:
The proposed feature would enable users to initiate a drag gesture on one of the selected dates and extend or shrink the date range by dragging horizontally across the calendar grid. As the user drags, the selected range dynamically updates to reflect the dragged selection, providing real-time feedback.

Use Cases:

Flexible Date Range Selection:

Users can easily adjust the date range by dragging the start or end date to include additional dates or shorten the range.
For example, a user may initially select a date range from January 1st to January 15th but later decide to extend it to January 20th by dragging the end date.
Efficient Range Modification:

When dealing with large date ranges, users can quickly modify the selection by dragging across the calendar grid, saving time compared to manually selecting each date.
For instance, when selecting a range spanning multiple months or years, users can efficiently adjust the range with a simple drag gesture.
Improved User Experience:

Introducing drag-based date range selection enhances the user experience by providing a more natural and intuitive interaction method.
Users can visually see the changes to the date range in real-time as they drag, reducing cognitive load and improving usability.
Consistency with Modern UI Patterns:

Drag-based interactions are a common and expected behavior in modern user interfaces, aligning with user expectations for intuitive interaction in calendar components.
This feature brings the calendar_date_picker2 package in line with contemporary UI design practices, enhancing its usability and appeal to developers and users alike.