build: introduced a single script to do the cloning/updating of all projects

also supporting developer trees

Signed-off-by: Alejandro Mery <amery@geeks.cl>
build: move branch iteration and pushing to central script

Signed-off-by: Alejandro Mery <amery@geeks.cl>
build: move updated checks to build.sh

Signed-off-by: Alejandro Mery <amery@geeks.cl>
build: always build if builddir is missing
run: call build.sh instead of build_foo.sh
linux: change build_linux.sh to be run once per build, by build.sh

Signed-off-by: Alejandro Mery <amery@geeks.cl>
u-boot: adjust script to run under build.sh

Signed-off-by: Alejandro Mery <amery@geeks.cl>