[ZEPPELIN-5420] Remove deprecated R module

### What is this PR for?
This module removes the deprecated R module.

### What type of PR is it?
-  Refactoring

### What is the Jira issue?
* https://issues.apache.org/jira/browse/ZEPPELIN-5420

### Questions:
* Does the licenses files need update? Yes
* Is there breaking changes for older versions? No
* Does this needs documentation? No

Author: Philipp Dallig <[email protected]>

Closes apache#4145 from Reamer/remove_r_module and squashes the following commits:

70153aa [Philipp Dallig] Remove deprecated R module

LICENSE

@@ -274,13 +274,6 @@ BSD 3-Clause licenses
 ========================================================================
 The following components are provided under the BSD 3-Clause license.  See file headers and project links for details.
 
-  (BSD 3 Clause) portions of rscala 1.0.6 (https://dahl.byu.edu/software/rscala/) - https://cran.r-project.org/web/packages/rscala/index.html
-   r/R/rzeppelin/R/{common.R, globals.R,protocol.R,rServer.R,scalaInterpreter.R,zzz.R }
-   r/src/main/scala/org/apache/zeppelin/rinterpreter/rscala/{Package.scala, RClient.scala}
-
-  (BSD 3 Clause) portions of Scala (http://www.scala-lang.org/download) - http://www.scala-lang.org/download/#License
-   r/src/main/scala/scala/Console.scala
-
   (BSD 3 Clause) diff.js (https://github.com/kpdecker/jsdiff)
 
   (BSD 3-Clause) Google Auth Library for Java (https://github.com/google/google-auth-library-java)

pom.xml

@@ -1852,21 +1852,6 @@
               <!-- package.json -->
               <exclude>**/package.json</exclude>
 
-              <!-- compiled R packages (binaries) -->
-              <exclude>**/R/lib/**</exclude>
-              <exclude>**/lib/rzeppelin/**</exclude>
-
-              <!--R-related files with alternative licenses-->
-
-              <exclude>**/R/rzeppelin/R/*.R</exclude>
-              <exclude>**/src/main/scala/scala/Console.scala</exclude>
-              <exclude>**/src/main/scala/org/apache/zeppelin/rinterpreter/rscala/Package.scala</exclude>
-              <exclude>**/src/main/scala/org/apache/zeppelin/rinterpreter/rscala/RClient.scala</exclude>
-
-               <!--The following files are mechanical-->
-              <exclude>**/R/rzeppelin/DESCRIPTION</exclude>
-              <exclude>**/R/rzeppelin/NAMESPACE</exclude>
-
               <exclude>zeppelin-jupyter-interpreter/src/main/resources/grpc/jupyter/*.py</exclude>
             </excludes>
           </configuration>