Add maxSelectedLabels, selectedItemsLabel and selectAll properties to MultiSelect

[mertsincan]

Name	Type	Default	Description
maxSelectedLabels	number	null	Decides how many selected item labels to show at most.
selectedItemsLabel	string	{0} items selected	Label to display after exceeding max selected labels.
selectAll	boolean	false	Whether all data is selected.

[mertsincan]

Fixed in c8421dc