linux-dmabuf-v1: add wlr_linux_dmabuf_feedback_v1_builder

This is a helper to generate feedback data. It's designed to be easy to use for compositors, and flexible enough to be extended in the future.

The struct wlr_linux_dmabuf_feedback_v1_builder needs to survive long enough, because it owns objects referenced from the generated struct wlr_linux_dmabuf_feedback_v1.

Closes: #3343 (closed)