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.

openair1/PHY/CODING/nrLDPC_coding/nrLDPC_coding_aal/CMakeLists.txt

@@ -1,3 +1,5 @@
+# SPDX-License-Identifier: LicenseRef-CSSL-1.0
+
 ##########################################################
 # LDPC offload library - O-RAN AAL/DPDK BBDEV
 ##########################################################

openair1/PHY/CODING/nrLDPC_coding/nrLDPC_coding_aal/README.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 This document highlights some of the key aspects of the implementation for O-RAN AAL/DPDK BBDEV; for user documentation, please consult the [setup guide](../../../../../doc/LDPC_OFFLOAD_SETUP.md) instead.
 
 ## Overview