radv: improve externalMemoryFeatures for android ahb

radv: improve externalMemoryFeatures for android ahb

VK_EXTERNAL_MEMORY_FEATURE_DEDICATED_ONLY_BIT should always be set, as
required by the spec.

VK_EXTERNAL_MEMORY_FEATURE_EXPORTABLE_BIT should be set when
radv_ahb_format_for_vk_format knowns the format.  That is,
radv_create_ahb_memory should at least know how to call
AHardwareBuffer_allocate.

VK_EXTERNAL_MEMORY_FEATURE_IMPORTABLE_BIT is always set.  We can't know
if gralloc can allocate the format/flags/usage combo or not (gralloc
might use a private format for the combo).

Fixed
dEQP-VK.api.external.memory.android_hardware_buffer.image_formats.*.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22619>