pipeline_vk: move call to create_attribute_descs() to ngli_pipeline_vk_init()
pipeline_vk: move call to create_attribute_descs() to ngli_pipeline_vk_init()

This will allow to re-use pipeline_graphics_init() later on.

gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl