Add new $IS_ONE_OF operator

[mainak55512]

Add a new $IS_ONE_OF operator to query if a field has one of the supplied values e.g. the query should be like name $IS_ONE_OF "Alex, Robert" which should give all that entries that have name value either 'Alex' or 'Robert'.

This operator should work on the following:

String: will check if string has one of the specified values.