Parse string representation of objects in method parameters

The query, find, count, aggregate, search, distinct, filterFields, sortQuery, updateSearched, findAndModify, reserveNextRecord, reserveNextID and deleteSearched methods have object parameters that can take filter objects with $ as part of the key. However, due to mongo restrictions, objects with $ cannot be used as filters if called from within IAP. This MR allows strings to be passed in as filter (which is parsed as Objects) which in turn allows users to send string representations of filter objects with $, from IAP.