Fixes: #3343 TextUtils.isEmpty creates problems when unit testing with Mockito (#3344)

* TextUtils: add mock textUtils for tests

* TextUtils: add more methods to mock for testing

* UploadControllerTest: fix the test resulting travis ci to fail

app/src/test/kotlin/fr/free/nrw/commons/upload/UploadControllerTest.kt

@@ -49,6 +49,7 @@ class UploadControllerTest {
     @Test
     fun startUpload() {
         val contribution = mock(Contribution::class.java)
+        `when`(contribution.getCreator()).thenReturn("Creator")
         uploadController!!.startUpload(contribution)
     }
 }