fix(docker): phySim image was always built on the latest of develop branch and not current code for merge requests
Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

This commit creates an intermediary build image for all eNB, gNB, UE,
nrUE, RU targets (ran-build) after the image containing all RAN
compilation dependencies (ran-base). Then, the corresponding target
container images are just copied from the ran-build.

The only exception is phySim, which is still compiled independently, as
the build_oai would otherwise put all compiled files into
phy_simulators/build instead of ran_build/build. We do this at this
state to avoid any inconsistencies.

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

Signed-off-by: Mohammed Ismail <mohammed.ismail@openairinterface.org>