Merge remote-tracking branch 'origin/e2_sub' into integration_2023_w27

.gitmodules

CMakeLists.txt

cmake_targets/build_oai

doc/README.md

executables/nr-softmodem.c

openair2/CMakeLists.txt

openair2/E2AP/CMakeLists.txt

openair2/E2AP/RAN_FUNCTION/CMakeLists.txt

openair2/E2AP/RAN_FUNCTION/CUSTOMIZED/CMakeLists.txt

openair2/E2AP/RAN_FUNCTION/CUSTOMIZED/ran_func_gtp.c

openair2/E2AP/RAN_FUNCTION/CUSTOMIZED/ran_func_gtp.h

openair2/E2AP/RAN_FUNCTION/CUSTOMIZED/ran_func_mac.c

openair2/E2AP/RAN_FUNCTION/CUSTOMIZED/ran_func_mac.h

openair2/E2AP/RAN_FUNCTION/CUSTOMIZED/ran_func_pdcp.c

openair2/E2AP/RAN_FUNCTION/CUSTOMIZED/ran_func_pdcp.h

openair2/E2AP/RAN_FUNCTION/CUSTOMIZED/ran_func_rlc.c

openair2/E2AP/RAN_FUNCTION/CUSTOMIZED/ran_func_rlc.h

openair2/E2AP/RAN_FUNCTION/CUSTOMIZED/ran_func_slice.c

openair2/E2AP/RAN_FUNCTION/CUSTOMIZED/ran_func_slice.h

openair2/E2AP/RAN_FUNCTION/CUSTOMIZED/ran_func_tc.c