Token auth (#434)

* Embed device platform information into token request

* Remove username and password from userProfile

* Display icon to show if profile has associated user token

* Remove username / password from login settings screen

* Refactor login procedure around token auth

* Refactoring

* Add profile login screen

- Username / password values are not stored
- Just to fetch api token

* Login with basic auth

* Pass profile to API when connecting

* Remove _BASE_URL accessor

- Fixes URL caching bug

* Add more context to login screen

* Add helper functions for unit tests

- Change default port to 8000 (makes testing easier with local inventree instance)

* api.dart handles basic auth now

* fix api_test.dart

* Further test improvements

* linting fixes

* Provide feedback when login fails

* More linting

* Record user details on login, and display in "about" widget

* Fix string lookup

* Add extra debug

* Fix auth values

* Fix user profile test

test/models_test.dart

@@ -5,7 +5,6 @@
 import "package:test/test.dart";
 
 import "package:inventree/api.dart";
-import "package:inventree/user_profile.dart";
 import "package:inventree/inventree/model.dart";
 import "package:inventree/inventree/part.dart";
 
@@ -16,16 +15,7 @@ void main() {
   setupTestEnv();
 
   setUp(() async {
-    await UserProfileDBManager().addProfile(UserProfile(
-      name: "Test Profile",
-      server: "http://localhost:12345",
-      username: "testuser",
-      password: "testpassword",
-      selected: true,
-    ));
-
-    assert(await UserProfileDBManager().selectProfileByName("Test Profile"));
-    assert(await InvenTreeAPI().connectToServer());
+    await connectToTestServer();
   });
 
   group("Category Tests:", () {