Allow user to customize format for displaying day of week above calendar

[rben01]

Is your feature request related to a problem? Please describe.
In the calendar widget that appears in obsidian’s sidebar, the days of the week above the calendar are always displayed with three letters (e.g., MON, TUE, WED). There is no way for the user to customize them to say e.g., M, T, W.

Describe the solution you'd like
Ideally this plugin would expose a setting for the user to input the Moment.js date format and use that to display the days of the week.

Describe alternatives you've considered
Overriding Obsidian’s CSS as follows:

#calendar-container > table.calendar {
	position: relative;
	top: -0.5lh;

	& > thead > tr > th {
		visibility: hidden;

		&::after {
			visibility: visible;
			display: block;
			line-height: initial;
		}

		&:nth-child(1)::after {
			content: "M";
		}
		&:nth-child(2)::after {
			content: "T";
		}
		/* etc */
	}
}