vec_iree: Add springbok_bytecode_module for tflite codegen

Wrap iree_bytecode_module with tflite extension detection, and add
iree-import-tflite to perform tflite codegen

Move the common iree-tranlate flags into default flags for
springbok_bytecode_module.

Change-Id: I0354d89bf00e56f80b8c6c934e54c329c89ef346