Storing detailed licensing information in SPDX headers and in the DEP5
file gives precise information to handle license compliance, but lacks a
high-level overview. Summmarize the licensing terms in a COPYING.rst
file to facilitate understanding of the libcamera project licenses, and
to clarify that closed-source third-party IPA modules are permitted.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Acked-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>