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.

common/utils/DOC/loader/devusage/api.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
  Loader API is defined in the [common/utils/load_module_shlib.h](https://gitlab.eurecom.fr/oai/openairinterface5g/blob/develop/common/utils/load_module_shlib.h) include file.
 ```c
 int load_module_shlib(char *modname,loader_shlibfunc_t *farray, int numf)

common/utils/DOC/loader/devusage/loading.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 Implementing a shared library dynamic load using the oai loader  is a two steps task:
 1.  define the `loader_shlibfunc_t` array, describing the list of externally available functions implemented in the library. This is the interface of the module.
 1.  Call the `load_module_shlib` function, passing it the previously defined array and the number of items in this array. The first argument to `load_module_shlib` is the name identifying the module, which is also used to format the corresponding library name, as described [here](loader/rtusage#shared-library-names)

common/utils/DOC/loader/devusage/struct.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 # `loader_shlibfunc_t`structure
 It is defined in include file [ common/util/load_module_shlib.h ](https://gitlab.eurecom.fr/oai/openairinterface5g/blob/develop/common/utils/load_module_shlib.h#L38). This structure is used  to list the symbols that should be searched by the loader when calling the `load_module_shlib` function.