Add wxRuby3 validator support, fix misc C++ validator problems

[Randalphwa]

This PR adds support for wxRuby3 validators. It also updates C++ code generation for validators:

• wxGenericValidator will ignore any validator styles
• wxFILTER_NONE is no longer added as a style if other styles are specified
• wx/filename.h is added to header file if validator_data_type is wxFileName
• it is no longer necessary to set both min and max values for numeric validators in order for either of them to be used.