[Bug Report] VCalendar regression in click handler when dealing with string categories

[gregveres]

Environment

Vuetify Version: 2.4.2
Last working version: 2.3.23
Vue Version: 2.6.12
Browsers: Edge 87.0.664.66
OS: Windows 10

Steps to reproduce

In v2.4, support for categories as objects was added. This seems to have introduced breaking changes to people who are using categories as an array of strings.
Specifically, I use the @mousedown:time-category event handler. This handler is passed an event with a category field. That field is now a category object always. The reproduction link above creates a simple calendar with 2 categories that are simple strings cat 1 and cat 2. The handler receives the event and dumps it to the console.

Note that when you click on the calendar, the event dumped to the console includes a category object with the name of the category in categoryName rather than category being a string as it used to be. This breaks all the code that used to process these events expecting the category to be a string.

Also, the docs have not been updated to reflect that category can be an object now and not just a string.

Expected Behavior

the object dumped to the console should have shown category: 'cat 1'

Actual Behavior

the object dumped to the console now shows category as an object:
{ categoryName: 'cat 1' }

Reproduction Link

https://codepen.io/gregveres-the-looper/pen/BaLVvjK?editors=1111

[KaelWD]

@nquinn721 This could be if (typeof category === 'string') return category right? You're already returning an array of bare strings a couple lines above.

vuetify/packages/vuetify/src/components/VCalendar/util/parser.ts

Lines 18 to 21 in 4542855

	if (typeof categories === 'string') return categories.split(/\s*,\s/)
	if (Array.isArray(categories)) {
	return categories.map((category: CalendarCategory) => {
	if (typeof category === 'string') return { categoryName: category }