[usecase-wrt][XWALK-1668][XWALK-1649][XWALK-1731]Add 3 tcs for wrt-usecase-tizen-tests

[Detailed commit message (if have)]
Impacted TCs num(approved): New 1, update 1, deleted 0
Impacted TCs num(designed): New 2, update 0, deleted 0
Unit test platform: [tizen]
Unit test result summary: Pass 2, Fail 0, Blocked 0
Merge pull request #863 from linshen/shenlin/usecase/audio-multiuser-pkgmgr

[usecase-wrt][XWALK-1668][XWALK-1649][XWALK-1731]Add 3 tcs for wrt-useca...
[wrt] Update suite.json for testapp
Merge pull request #876 from kangxu/kangxu/wrt/testappfolder/add

[wrt] Update suite.json for testapp