customParseFormat: added logic to parse the week day

[waseemahmad31]

Resolves issue #571

import customParseFormat from 'dayjs/plugin/customParseFormat';
dayjs.extend(customParseFormat);

var fmt = 'dddd DD MMMM HH:mm';

var d = dayjs('Tuesday 16 January 18:00', fmt);
// works fine: d.isValid() is true

d = dayjs('Monday 15 January 18:00', fmt);
// works fine: d.isValid() is true

d = dayjs('Saturday 20 January 18:00', fmt);
// works fine: d.isValid() is true

[waseemahmad31]

test case failing with moment 2.24.0.

I have checked with moment 2.5.1. It's working.
https://jsfiddle.net/pkje2y6z/

[BePo65]

What would be the use of parsing the weekday?

Wouldn't it be better to parse variable length text (e.g. the name of a weekday) like in issue #571 ?