Move GetConfigPath to GetAppPath (applications directory)

BUG: XWALK-2672

Change-Id: Iee497d8f5744b1d8c4533fe7f6009040b0bcf826
Signed-off-by: Sabera Djelti (sdi2) <sabera.djelti@open.eurogiciel.org>
And you need declare `uid` and `GLOBAL_USER` at all because they only used once. plz rewrite as
```
const char* app_path = getuid() != tzplatform_getuid(TZ_SYS_GLOBALAPP_USER) ?
                       tzplatform_getenv(TZ_USER_APP) :
                       tzplatform_getenv(TZ_SYS_RW_APP);
```