Allow to pass the function to get coordinates in .locate()

[Nisgrak]

Is your feature request related to a problem? Please describe.
I'm making a web app with Capacitor and https didn't work in iOS so can't use navigator.geolocation.getCurrentPosition() but Capacitor exposes that in his modules, so I can get the coordinates, but not with the function leaflet uses

Describe the solution you'd like
A new option in locate config to overwrite the function to read the coordinates in

Leaflet/src/map/Map.js

Lines 660 to 665 in bdd7ebf

	if (options.watch) {
	this._locationWatchId =
	navigator.geolocation.watchPosition(onResponse, onError, options);
	} else {
	navigator.geolocation.getCurrentPosition(onResponse, onError, options);
	}

Describe alternatives you've considered
I try to use https in iOS Capacitor but in the issues the devs say that didn't work anyways

Additional context
I think that the code would be something like this:

this.map.locate({
    getCoordinates: async (onResponse, onError, options) => {
        return await Geolocation.getCurrentPosition(); // Return the same as navigator.geolocation.getCurrentPosition()
    }
})

if (options.getCoordinates) {
    if (options.watch) {
        this._locationWatchId = options.getCoordinates(options);

    } else {
        try {
            var pos = await options.getCoordinates(options);
            onResponse(pos);

        } catch (error) {
            onError(error);

        }
    }
} else {
    if (options.watch) {
        this._locationWatchId =
            navigator.geolocation.watchPosition(onResponse, onError, options);

    } else {
        navigator.geolocation.getCurrentPosition(onResponse, onError, options);

    }
}