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/telnetsrv/DOC/telnetaddcmd.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 # code example of adding a command to the telnet server
 
 The following example is extracted from [the oai `openair1/PHY/CODING/coding_load.c` file](https://gitlab.eurecom.fr/oai/openairinterface5g/blob/develop/openair1/PHY/CODING/coding_load.c).

common/utils/telnetsrv/DOC/telnetarch.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 # telnet server principles
 
 The oai telnet server is implemented in shared libraries to be loaded by the [oai shared library loader](loader). `libtelnetsrv.so ` contains the code common to all oai softmodem executables, where `libtelnetsrv_<app>.so` contains the code specific to the executable identified by `app`. 

common/utils/telnetsrv/DOC/telnetgetset.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 getall command can be used to get the list of variables that can bet set or get from the telnet shell. Knowing the names of the variables they can then be set or read. Setting a variable is not always relevant, the telnet server doesn't provide a mechanism to restrict the set command.
 
 ```bash

common/utils/telnetsrv/DOC/telnethelp.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 # oai telnet server global help
 
 ``` bash

common/utils/telnetsrv/DOC/telnethist.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 The telnet server implements a simple history system
 ```bash
 softmodem> telnet history list

common/utils/telnetsrv/DOC/telnetloader.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 loader command can be used to check loader configuration parameters and the list of loaded shared libraries and for each library the list of available functions.
 
 ```bash

common/utils/telnetsrv/DOC/telnetlog.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 The log command can be used to get the status of the log parameters and to dynamically modify these parameters. The log command has its own [help](telnethelp.md#oai-telnet-server-specific-commands-help)
 ```bash
 softmodem>  softmodem log disable 0-35

common/utils/telnetsrv/DOC/telnetloop.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 The telnet server includes a **_loop_** command that can be used to iterate a given command. The number of iterations and the delay, in ms between two iterations can be modified, as shown in the following example:
 
 ```bash

common/utils/telnetsrv/DOC/telnetmeasur.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 measur command can be used to get cpu usage or signal processing statistics from a running eNB instance.
 
 

common/utils/telnetsrv/DOC/telneto1.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 [[_TOC_]]
 
 The telnet O1 module (`telnetsrv_o1.c`) can be used to perform some O1-related

common/utils/telnetsrv/DOC/telnetsrv.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 The oai embedded telnet server is an optional monitoring and debugging tool. It provides a simple Command Line Interface to the oai softmem. New commands can easily be added by developers to the telnet server.
 
 * [Using the telnet server](telnetusage.md)

common/utils/telnetsrv/DOC/telnetusage.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 # starting the softmodem with the telnet server
 By default the embedded telnet server, which is implemented in a shared library, is not built. It can be built after compiling the softmodem executable using the `build_oai` script: