Draft: Create input for phone verification

What does this MR do and why?

1. Follows from !96529 (merged). In this MR, I have created a Vue component to enter in the verification code we will send to users.
2. The user can also go back to edit their phone number.

Screenshots or screen recordings

Screen_Recording_2022-09-20_at_12.49.06_pm

How to set up and validate locally

1. Turn on SaaS mode with

export GITLAB_SIMULATE_SAAS=1

1. Turn on feature flag

bundle exec rails c
> Feature.enable(:identity_verification)

1. Sign in as a user and navigate to http://localhost:3000/users/identity_verification

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Partially resolves https://gitlab.com/gitlab-org/modelops/anti-abuse/team-tasks/-/issues/79 & https://gitlab.com/gitlab-org/modelops/anti-abuse/team-tasks/-/issues/78