Fix photo & camera permission management (#140)

* Check photo & camera perms and alert the user if not available (close #64)

- Adds perms checks with a prompt to update settings if needed
- Moves initial access of photos in the composer so that the initial prompt
  occurs at an intuitive time.

* Add react-native-permissions test mock

* Fix issue causing multiple access requests

* Use longer var names

* Update podfile.lock

* Lint fix

* Move photo perm request in composer to the gallery btn instead of when the carousel is opened

package.json

@@ -56,6 +56,7 @@
     "react-native-inappbrowser-reborn": "^3.6.3",
     "react-native-linear-gradient": "^2.6.2",
     "react-native-pager-view": "^6.0.2",
+    "react-native-permissions": "^3.6.1",
     "react-native-progress": "^5.0.0",
     "react-native-reanimated": "^2.9.1",
     "react-native-root-siblings": "^4.1.1",