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/config/DOC/config.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 # OAI configuration module
 
 The configuration module provides an api that other oai components can use to get parameters at init time. It defines a parameter structure, used to describe parameters attributes (for example name and  type). The same structure includes a pointer to the variable where the configuration module writes the parameter value, at run time, when calling config_get or config_getlist functions. For each parameter a function to check the value can be specified and pre-defined functions  are provided for some common parameter validations (integer in a range or in a list, string in a list).  The module also include an api to check that no unknown options have been entered on the command line and a a mechanism to display a help text for suppoted parameters.

common/config/DOC/config/arch.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 # config module source files
 ![configmodule_srcdir](/uploads/fdc3e96011fd5592440900dfa05b4701/configmodule_srcdir.png)
 # config module components

common/config/DOC/config/devusage.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 The configuration module objectives are
 1. Allow easy parameters management in oai, helping the development of a flexible, modularized and fully configurable softmodem.
 2. Use a common configuration API in all oai modules

common/config/DOC/config/devusage/addaparam.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 To add a new parameter in an existing section you  insert an item in a `paramdef_t` array, which describes the parameters to be read in the existing `config_get` call. You also need to increment the numparams argument.
 
 existing code:

common/config/DOC/config/devusage/addparamset.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 The configuration module maps a configuration file section to a `paramdef_t` structure array. One `config_get` call can be used to return the values of all the parameters described in the `paramdef_t` array.
 Retrieving a single occurence of a parameter set ( a group in the libconfig terminology) is just a two steps task:
 1.  describe the parameters in a `paramdef_t` array

common/config/DOC/config/devusage/api.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 ## config module management
 
 ```c

common/config/DOC/config/devusage/struct.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 # `paramdef_t`structure
 It is defined in include file [ common/config/config_paramdesc.h ](https://gitlab.eurecom.fr/oai/openairinterface5g/blob/develop/common/config/config_paramdesc.h#L103). This structure is used by developers to describe parameters and by the configuration module to return parameters value. A pointer to a `paramdef_t` array is passed to `config_get` and `config_getlist` calls to instruct the configuration module what parameters it should read.
 

common/config/DOC/config/rtusage.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
 [[_TOC_]]
 
 # General usage