LG-768 Create event for personal key as 2FA

[monfresh]

Why: To make it easier to query if any particular users have used
their personal key to sign in, and to add an event to the user's account
page for visibility.

Hi! Before submitting your PR for review, and/or before merging it, please
go through the checklists below. These represent the more critical elements
of our code quality guidelines. The rest of the list can be found in
CONTRIBUTING.md

• When adding a new controller that requires the user to be fully
  authenticated, make sure to add before_action :confirm_two_factor_authenticated
  as the first callback.

• Unsafe migrations are implemented over several PRs and over several
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• Indexes were added if necessary. This article provides a good overview
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• Verified that the changes don't affect other apps (such as the dashboard)

• When relevant, a rake task is created to populate the necessary DB columns
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  who might not have interacted with this column yet (such as users who have not
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• Migrations against existing tables have been tested against a copy of the
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  issues. In that case, all the migration did was add a new column and an index to
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• The changes are compatible with data that was encrypted with the old code.

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• Tests added for this feature/bug

• Prefer feature/integration specs over controller specs

• When adding code that reads data, write tests for nil values, empty strings,
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[jgsmith-usds]

Other than the question about tests, this looks good to me.

[stevegsa]

LGTM