Migrate JSHandle APIs to async

[inancgumus]

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1. Async JSHandle prepare #1365
   mapping refactor stability +3
   
2. Async JSHandle #1366
   async mapping +2
   
3. Create documentation for the JSHandle class #764
   1 of 1
   documentation good first issue hacktoberfest +3
   
4. Update JSHandle to return Promises k6-DefinitelyTyped#56
   +0
5. Release Notes:

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What

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

Class	Method	Current k6 Return	PW return
JSHandle	asElement	ElementHandle|null	TextendsNode?ElementHandle:null
JSHandle	dispose	void	Promise
JSHandle	evaluate<R, Arg>	R	not found in Playwright
JSHandle	evaluateHandle<R, Arg>	JSHandle	not found in Playwright
JSHandle	getProperties	Map<string,JSHandle>	Promise<Map<string,JSHandle>>
JSHandle	jsonValue	any	Promise

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