Minor Improvements

[cbhernan]

What does this PR do?

• Update authmethods call to a GET instead of POST
• Use import syntax instead of require for cloud functions
• Filter out first party app prior to making requests to find out if it is a first party app when we already know that it is.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 80.51%. Comparing base (37af656) to head (082fb1a).

Files	Patch %	Lines
lib/controllers/auth0_user_api_implementation.dart	0.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## development #103 +/- ## =============================================== + Coverage 80.42% 80.51% +0.08% =============================================== Files 16 16 Lines 981 980 -1 =============================================== Hits 789 789 + Misses 192 191 -1 ```

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