[usecase-wrt]move usecase to separate folder

[Detailed commit message (if have)]
Impacted TCs num(approved): move all usecase to separate folder
Unit test platform: [android]
Unit test result summary: Pack to apk and isntall to verify the page showing ok
Merge pull request #518 from linshen/update-usecase-android

[usecase-wrt]move usecase to separate folder