Grant only necessary permission and use UiAutomation for it

`pm` is less effective, according to logs

Author: wzieba

app/src/androidTest/kotlin/org/wordpress/aztec/demo/BaseTest.kt

@@ -2,18 +2,23 @@
 
 package org.wordpress.aztec.demo
 
+import android.Manifest.permission.CAMERA
 import android.util.Log
-import androidx.test.rule.GrantPermissionRule
+import androidx.test.platform.app.InstrumentationRegistry
 import androidx.test.runner.AndroidJUnit4
-import org.junit.Rule
+import org.junit.Before
 import org.junit.runner.RunWith
 
 @RunWith(AndroidJUnit4::class)
 abstract class BaseTest {
-    @Rule
-    @JvmField
-    val grantPermissionRule: GrantPermissionRule = GrantPermissionRule.grant(android.Manifest.permission.CAMERA,
-            android.Manifest.permission.WRITE_EXTERNAL_STORAGE)
+
+    @Before
+    fun grantPermissions() {
+        val (uiAutomation, packageName) = with(InstrumentationRegistry.getInstrumentation()) {
+            Pair(uiAutomation, targetContext.packageName)
+        }
+        uiAutomation.grantRuntimePermission(packageName, CAMERA)
+    }
 
     companion object {
         fun label(label: String) {