feat(jans-config-api): write the missing test cases of admin-ui plugin

[duttarnab]

• Write the missing test cases of admin-ui plugin

admin-ui-plugin-tests/
├── pom.xml
└── src/test/
    ├── java/io/jans/ca/plugin/adminui/
    │   ├── rest/
    │   │   ├── AdminUIRoleResourceTest.java          (16 TCs)
    │   │   ├── AdminUIPermissionResourceTest.java    (16 TCs)
    │   │   ├── AdminUIRoleMappingResourceTest.java   (18 TCs)
    │   │   ├── AdminUIConfigResourceTest.java        (11 TCs)
    │   │   └── license/
    │   │       └── LicenseResourceTest.java          (20 TCs)
    │   ├── service/
    │   │   └── AdminUIRoleServiceTest.java           (11 TCs)
    │   └── integration/
    │       └── AdminUIPluginLifecycleTest.java       (10 TCs)
    └── resources/
        └── testng.xml