HSEARCH-436 Implementing public metadata APIs related to type and field metadata as well as index metadata

Adding additonal methods to FieldDescriptor (getIndex, isNumeric, precicionStep)
Moving precisionstep and null token from PropertyMetadata into DocumentFieldMetadata
HSEARCH-1355 Renaming EntityIndexBinder into EntityIndexBinding

Also deprecating EntityIndexBinder related methods in SearchFactoryIntegrator and SearchFactoryImplementor