Change OAI license to CSSL v1.0 (and others)

- all RAN code, CI code, configuration files, dockerfiles, in CSSL v1.0
- all deployment code (openshift, charts, ancillary files like shell
  scripts), in MIT
- documentation in CC-BY-4.0
- exceptions might apply and are listed in NOTICE
- there is a new LICENSES folder with all licenses
- CONTRIBUTIONS.md has been updated accordingly

For automated changes based on OAI PL v1.1:

    perl -i~ -0pe 's/\/\*.*Licensed to the OpenAirInterface.*openairinterface.org\n#?/\/*\n * SPDX-License-Identifier: LicenseRef-CSSL-1.0\n/s' **/*.{c,h,cpp}
    perl -i~ -0pe 's/\/\*.*Licensed to the OpenAirInterface.*openairinterface.org\n#?/\/*\n * SPDX-License-Identifier: LicenseRef-CSSL-1.0\n/s' **/*.ts
    perl -i~ -0pe 's/<!--.*Licensed to the OpenAirInterface.*openairinterface.org\n.*-->/<!-- SPDX-License-Identifier: LicenseRef-CSSL-1.0 -->/s' **/*.xml

The rest (cmake, files with missing license, cmake) manually.

tools/docker-dev-env/Dockerfile

@@ -1,3 +1,5 @@
+# SPDX-License-Identifier: LicenseRef-CSSL-1.0
+
 FROM ran-base:latest
 ARG USERNAME=root
 ARG USER_UID=1000

tools/docker-dev-env/README.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 # Containerized development environment for OAI
 
 ## Description

tools/docker-dev-env/bootstrap.sh

@@ -1,4 +1,6 @@
 #!/bin/bash
+# SPDX-License-Identifier: MIT
+
 set -e
 CONTAINER_NAME=openair-dev-$USER
 if [ "$EUID" -eq 0 ]; then

tools/docker-dev-env/docker-compose.yml

@@ -1,3 +1,5 @@
+# SPDX-License-Identifier: MIT
+
 services:
   openair-dev-env:
     container_name: "openair-dev-${USER}"