ZEPPELIN-3147. Added Checkstyle to the angular module
ZEPPELIN-3147. Added Checkstyle to the angular module

### What is this PR for?
Added Checkstyle to the **angular** module. Did not have to fix any errors or warnings.

### What type of PR is it?
Improvement

### Todos
* [ ] - Task

### What is the Jira issue?
* https://issues.apache.org/jira/browse/ZEPPELIN-3147

### How should this be tested?
* CI pass

### Screenshots (if appropriate)

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

Author: Jan Hentschel <jan.hentschel@ultratendency.com>

Closes #2766 from HorizonNet/ZEPPELIN-3147 and squashes the following commits:

b766924 [Jan Hentschel] ZEPPELIN-3147. Added Checkstyle to the angular module

datalayer/zeppelin-datalayer,mwkang/zeppelin,datalayer/zeppelin-datalayer,apache/incubator-zeppelin,tinkoff-dwh/zeppelin,fogbeam/zeppelin_mirror,Leemoonsoo/zeppelin,zetaris/zeppelin,hammertank/zeppelin,sergeymazin/zeppelin,mwkang/zeppelin,lresende/incubator-zeppelin,prabhjyotsingh/zeppelin,fogbeam/zeppelin_mirror,lresende/incubator-zeppelin,jongyoul/incubator-zeppelin,lresende/incubator-zeppelin,zjffdu/zeppelin,cquptEthan/incubator-zeppelin,mwkang/zeppelin,herval/zeppelin,VipinRathor/zeppelin,tinkoff-dwh/zeppelin,hammertank/zeppelin,prabhjyotsingh/incubator-zeppelin,zjffdu/zeppelin,cquptEthan/incubator-zeppelin,r-kamath/zeppelin,zetaris/zeppelin,r-kamath/incubator-zeppelin,sergeymazin/zeppelin,r-kamath/incubator-zeppelin,apache/incubator-zeppelin,jongyoul/zeppelin,fogbeam/zeppelin_mirror,r-kamath/zeppelin,r-kamath/zeppelin,Leemoonsoo/incubator-zeppelin,karuppayya/zeppelin,apache/zeppelin,zetaris/zeppelin,Leemoonsoo/zeppelin,karuppayya/zeppelin,mwkang/zeppelin,fogbeam/zeppelin_mirror,zjffdu/zeppelin,cquptEthan/incubator-zeppelin,tinkoff-dwh/zeppelin,lresende/incubator-zeppelin,prabhjyotsingh/zeppelin,herval/zeppelin,zetaris/zeppelin,tinkoff-dwh/zeppelin,prabhjyotsingh/zeppelin,fogbeam/zeppelin_mirror,apache/zeppelin,prabhjyotsingh/incubator-zeppelin,r-kamath/incubator-zeppelin,herval/zeppelin,prabhjyotsingh/zeppelin,VipinRathor/zeppelin,Leemoonsoo/incubator-zeppelin,sergeymazin/zeppelin,zetaris/zeppelin,Leemoonsoo/zeppelin,prabhjyotsingh/incubator-zeppelin,zetaris/zeppelin,zetaris/zeppelin,datalayer/zeppelin-datalayer,jongyoul/zeppelin,apache/incubator-zeppelin,r-kamath/incubator-zeppelin,herval/zeppelin,jongyoul/incubator-zeppelin,apache/zeppelin,cquptEthan/incubator-zeppelin,r-kamath/incubator-zeppelin,jongyoul/incubator-zeppelin,hammertank/zeppelin,prabhjyotsingh/incubator-zeppelin,hammertank/zeppelin,sergeymazin/zeppelin,zjffdu/zeppelin,prabhjyotsingh/incubator-zeppelin,Leemoonsoo/zeppelin,jongyoul/zeppelin,datalayer/zeppelin-datalayer,VipinRathor/zeppelin,mwkang/zeppelin,zjffdu/zeppelin,apache/incubator-zeppelin,mwkang/zeppelin,VipinRathor/zeppelin,sergeymazin/zeppelin,zjffdu/zeppelin,cquptEthan/incubator-zeppelin,cquptEthan/incubator-zeppelin,jongyoul/incubator-zeppelin,hammertank/zeppelin,Leemoonsoo/zeppelin,cquptEthan/incubator-zeppelin,apache/zeppelin,jongyoul/incubator-zeppelin,tinkoff-dwh/zeppelin,mwkang/zeppelin,VipinRathor/zeppelin,Leemoonsoo/incubator-zeppelin,lresende/incubator-zeppelin,apache/zeppelin,fogbeam/zeppelin_mirror,joroKr21/incubator-zeppelin,apache/zeppelin,Leemoonsoo/incubator-zeppelin,joroKr21/incubator-zeppelin,joroKr21/incubator-zeppelin,prabhjyotsingh/incubator-zeppelin,lresende/incubator-zeppelin,r-kamath/zeppelin,lresende/incubator-zeppelin,Leemoonsoo/incubator-zeppelin,hammertank/zeppelin,r-kamath/incubator-zeppelin,sergeymazin/zeppelin,herval/zeppelin,r-kamath/zeppelin,Leemoonsoo/zeppelin,prabhjyotsingh/zeppelin,joroKr21/incubator-zeppelin,karuppayya/zeppelin,jongyoul/incubator-zeppelin,joroKr21/incubator-zeppelin,karuppayya/zeppelin,jongyoul/zeppelin,Leemoonsoo/zeppelin,joroKr21/incubator-zeppelin,joroKr21/incubator-zeppelin,karuppayya/zeppelin,VipinRathor/zeppelin,herval/zeppelin,herval/zeppelin,prabhjyotsingh/zeppelin,r-kamath/incubator-zeppelin,tinkoff-dwh/zeppelin,r-kamath/zeppelin,joroKr21/incubator-zeppelin,apache/zeppelin,hammertank/zeppelin,karuppayya/zeppelin,r-kamath/zeppelin,jongyoul/zeppelin,Leemoonsoo/zeppelin,zjffdu/zeppelin,jongyoul/zeppelin,prabhjyotsingh/zeppelin,sergeymazin/zeppelin,apache/incubator-zeppelin,tinkoff-dwh/zeppelin,fogbeam/zeppelin_mirror,Leemoonsoo/incubator-zeppelin,karuppayya/zeppelin,apache/incubator-zeppelin,jongyoul/zeppelin,VipinRathor/zeppelin