AO3-7222 This fix hides the Rename button when unauthorized

[Mangooomango]

Only display Rename when policy(@user).can_change_username?

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[omerfaruk-pseud]

Hi, Mangooomango!

Thank you so much for this pull request. Someone will be along to review it soon.

I've updated the Jira issue status to In Review to make sure no one mistakenly creates a duplicate pull request. If you'd like the ability to comment on, assign, and transition issues in the future, you're welcome to create a Jira account! It makes things a bit easier for us on the organizational side if the Full Name on your Jira account either closely matches the name you'd like us to credit in the release notes or includes it in parentheses, e.g. "Nickname (CREDIT NAME)."

Once you've done that (or if you've already done it -- Jira has been unreliable about showing us new accounts in the admin panel lately), you can either reply here or send an email to otw-coders@transformativeworks.org with both your account name and email address and we'll set up the permissions for you.

Can you also edit your pull request comment so that it follows our pull request template? Namely, add the correct link to the Jira issue, add the purpose and remove the sections you don't fill.

Thanks again for contributing! If you have any questions, you can contact us at the same email address listed above.

[omerfaruk-pseud]

Thank you! Can you also add automated tests in accordance to our coding standards? Since this changes the behaviour of a button, integration tests are needed so it can automatically check if it's displayed correctly.