fix(share): Prevent share if sharing in progress

[jcesarmobile]

If you call share twice in a row it causes issues, on android two sheets appear but both return the result of the first one, on iOS the second one is not presented and the promise never resolves nor rejects.

This PR detects if a share is in progress and prevent it rejecting with an error-

closes #323

[qliqdev]

While inapp browser is opened share is not working

throwing

Can't share while sharing is in progress, event if Share.canShare() returns {value: true}

capacitor-plugins/share/ios/Sources/SharePlugin/SharePlugin.swift

Lines 67 to 70 in 2fe419b

	if self?.bridge?.viewController?.presentedViewController != nil {
	call.reject("Can't share while sharing is in progress")
	return
	}

is this expression right?