feat(DIA-903): One-Shot Facebook Login

[iskounen]

This PR resolves DIA-903

Description

This PR adds one-shot Facebook Login to Eigen.

iOS	Android
https://github.com/user-attachments/assets/465b4696-4c10-43a4-b6a3-d03d7755604d	https://github.com/user-attachments/assets/bcc3f997-3670-4e49-a6e3-a137949e700f

PR Checklist

• I have tested my changes on iOS and Android.
• I hid my changes behind a feature flag, or they don't need one.
• I have included screenshots or videos, or I have not changed the UI.
• I have added tests, or my changes don't require any.
• I added an app state migration, or my changes do not require one.
• I have documented any follow-up work that this PR will require, or it does not require any.
• I have added a changelog entry below, or my changes do not require one.

To the reviewers 👀

• I would like at least one of the reviewers to run this PR on the simulator or device.

Changelog updates

Changelog updates

Cross-platform user-facing changes

iOS user-facing changes

Android user-facing changes

Dev changes

• Implemented one-shot facebook login for auth2 - iskounen

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[ArtsyOpenSource]

This PR contains the following changes:

• Dev changes (Implemented one-shot facebook login for auth2 - iskounen - iskounen)

Generated by 🚫 dangerJS against 5d56353

[damassi]

🦑

[iskounen]

I'm going to continue working on this helper when I get to social account linking (it's ticketed), so in the meantime I decided to console log these variables so that I can suppress errors without commenting-out the whole file.

[damassi]

One minor request to clean up the ;(Foo.bar as jest.Mock).thing() repeat aliasing in tests, but otherwise code looks great 👍