[embedding][XWALK-2381] Change loadAppFromManifest mode to sync and improve pack.sh and loadUrl

Impacted tests(approved): new 0, update 1, delete 0
Unit test platform: [Android]
Unit test result summary: pass 84, fail 18, block 4
[usecase-webapi] Remove two unused subcase tags for usecase

Impacted TCs num(approved): New 0, Update 2, Delete 0
Unit test Platform: [Andriod]
Unit test result summary: Pass 2, Fail 0, Blocked 0
Merge pull request #807 from JianfengXu/xujf/usecase/subcase

[usecase-webapi] Remove two unused subcase tags for usecase
Merge pull request #771 from zhuyongyong/yongzhu/embeddingAPI-tests/loadUrl

[embedding][XWALK-2381] Change loadAppFromManifest mode to sync and improve pack.sh