[BUG] Type signature for stopTrackEvent is incorrect

[GravlLift]

Description/Screenshot
The properties parameter is of type {[key: string]: string}

ApplicationInsights-JS/shared/AppInsightsCommon/src/Interfaces/IAppInsights.ts

Line 28 in ed8632a

stopTrackEvent(name: string, properties?: {[key: string]: string}, measurements?: {[key: string]: number}): void;

Per the README.md, "objects are okay too".

ApplicationInsights-JS/README.md

Lines 270 to 284 in ed8632a

	When using stopTrackPage and stopTrackEvent, you can pass in data categorized by types:
	Strings: These should be included under the properties field.
	Numbers: Add these under the measurements field.
	Remember, the order of the properties and measurements should not be altered. You can achieve this using the following code structure:
	```js
	appInsights.startTrackEvent("event name");
	appInsights.stopTrackEvent("event name", {
	stringProp1: 'string',
	stringProp2: {nested:"objects are okay too"}
	},
	{numProp1: 3.15, numProp2: 90000}
	)
	```

Expected behavior
Testing reveals that nested objects are handled just fine here. Perhaps the signature should be updated to match trackEvent's customProperties parameter of type {[key: string]: any}?

Additional context
All links and testing in version 3.3.3