Migrate Locator APIs to async

[inancgumus]

Tasks

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1. Prepare Locator for async migration #1330
   mapping refactor stability +3
   
2. Async Locator #1332
   async breaking mapping +3
   
3. Update to Async Locator k6-docs#1591
   Area: browser +1
   
4. Update methods on Locator type to return Promises k6-DefinitelyTyped#46
   browser +1
   
5. Add release notes

---

What

Migrate the following APIs according to the How section in #428:

Class	Method	Current k6 Return	PW return
Locator	clear	void	Promise
Locator	dblclick	void	Promise
Locator	check	void	Promise
Locator	uncheck	void	Promise
Locator	isChecked	boolean	Promise
Locator	isDisabled	boolean	Promise
Locator	isEditable	boolean	Promise
Locator	isEnabled	boolean	Promise
Locator	isHidden	boolean	Promise
Locator	isVisible	boolean	Promise
Locator	fill	void	Promise
Locator	focus	void	Promise
Locator	getAttribute	string|null	Promise<null|string>
Locator	innerHTML	string	Promise
Locator	innerText	string	Promise
Locator	textContent	string	Promise<null|string>
Locator	inputValue	string	Promise
Locator	selectOption	string[]	Promise<Array>
Locator	press	void	Promise
Locator	type	void	Promise
Locator	hover	void	Promise
Locator	dispatchEvent	void	Promise
Locator	waitFor	void	Promise

For details on the Why and How, check the overarching issue in #428.