agl-compositor: Move protocol files to the -dev package

agl-compositor: Move protocol files to the -dev package

Bug-AGL: SPEC-4015

v2 (jsmoeller): simplify protocols recipe
v3 (jsmoeller): pkgconfig needs to be in the protocols package
v4 (mvlad): Re-phrase the commit description
v5 (mvlad): leave DEPENDS alone
v6 (smurray): Untagle commit message

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Change-Id: I21fa9b40ad07871b956abcbb4e79c8f5d742522c
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/26490
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Tested-by: Jenkins Job builder account