icd:Add support for extended features queries

icd:Add support for extended features queries

Update mock ICD generator so that if we have an extension that's been
promoted to core, the core version will call any existing custom
implementation of the extension function.

Update Features query to detect the two existing extension structs
(VkPhysicalDeviceDescriptorIndexingFeaturesEXT and
VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT) and enable all of
those features when those queries are present.