Query Arguments array should be converted to a type safe object

[ernestmarcinko]

Sor far the query arguments had been passed as an array, which lacks any type safety from development standpoint. This is passed to the asp_query_args hook.

A new data model should be introduced for this, which implements the ArrayAccess interface in a way, that the properties still can be accessed and modified as array elements.

• Make an ArrayAccess implementation for the SearchQueryArgs model
• Move all items from SearchQuery::$defaults to SearchQueryArgs model
• Implement the new model into SearchQuery
• Check all arguments one-by-one for any type safety issues
• Test extensively on all different configurations
• Update asp_query_args documentation with type safe declarations
• Update ASP_Query documentation