feat: add new edgesOnly to return only start/end dates in selection range

[ghiscoding]

• when using multiple-ranged, it will by default push all the range dates in the settings.selected.dates, however in some cases we are sometime only interested in the Start/End dates (first & last). For example, if we have a range of Jan 1st to Feb 28, it will push 59 days to the settings.selected.dates array, however with edgesOnly, it will only push 2 dates in the array which are equal to the Start/End dates
• for a project like mine with a data grid, I'm only interested in the Start/End dates so that I can use it to filter my grid data by comparing dates between X start date and Y end date. So I'm really only interested in the edges (start/end) and I don't care about the dates that are in the middle, I really don't need to know what the dates are in the middle dates since the start/end is all I really need (hence why I'm adding this new feature)
• this option can be extremely useful when the user selects a date range that spans over multiple months (6 months or 1 year range would create a very large array of selected dates, when in reality we sometime just want to know the date range start/end dates for filtering purposes or anything similar)
• Note: I'm already using this code in production from my fork of your project, I hope to switch back to your original project as soon as all my PRs are hopefully accepted :)

Below is an example making a date range selection which starts on April 4th and ends on April 14th

with edgesOnly: true, it will return only 2 dates in the array, the start & ending dates. I can then call this simple line of code to retrieve start/end dates const [start, end] = self.selectedDates;

but without edgesOnly (false or undefined which is the default), it will return all dates in the array

[uvarov-frontend]

I returned the wrong indentation to get rid of the eslint error, although I agree that your indentation is correct.