Bug 1878910: Fixes duplicate FxA sessions

[tarikeshaq]

Passes on the LOGIN web channel message to the fxa component, setting the user's session token. Also stops requesting the session scope, when singing in using email and password

NOTE: This should not land until, the following is true.. to make sure of that, I'm keeping this a draft till then

• Tests are added if possible
• Recieves session token from application before oauth for user agents mozilla/application-services#6111 is landed and
• FxA's Train 1.277.1 is in production for testing, I'll confirm here once that's true (should be on Feb 7th)

Pull Request checklist

• Quality: This PR builds and passes detekt/ktlint checks (A pre-push hook is recommended)
• Tests: This PR includes thorough tests or an explanation of why it does not
• Changelog: This PR includes a changelog entry or does not need one
• Accessibility: The code in this PR follows accessibility best practices or does not include any user facing features

After merge

• Breaking Changes: If this is a breaking Android Components change, please push a draft PR on Reference Browser to address the breaking issues.

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GitHub Automation

https://bugzilla.mozilla.org/show_bug.cgi?id=1878910

[tarikeshaq]

Will migrate this patch to Phab :)