fix(settings): change Mastodon only URI to webfinger

[TechnicalSuwako]

• Resolves: [Bug]: "Faith could not update fediverse (e.g. mastodon)" #53107

Summary

The URI for Mastodon only has been changed to the URI used for all Fediverse servers.
https://{$instance}/api/v1/accounts/lookup?acct={$username}@{$instance} → https://{$instance}.well-known/webfinger?resource=acct:{$username}@{$instance}

TODO

• ...

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[joshtrichards]

Thanks @TechnicalSuwako. This change does seem to make sense.

Can you adjust the commit message to be in conventional format?

Refs:

https://swicg.github.io/activitypub-webfinger/
https://docs.joinmastodon.org/spec/webfinger/

[TechnicalSuwako]

@joshtrichards What does the "traditional format" look like?
I use an automatic translation machine...

[susnux]

Code looks good, thank you.
But please fix the tests

There were 2 errors:

1. Test\Accounts\AccountManagerTest::testSanitizingFediverseServer with data set "valid response" ('@foo@example.com', 'foo@example.com', true, '{"username":"foo"}')
   InvalidArgumentException: fediverse

/home/runner/actions-runner/_work/server/server/lib/private/Accounts/AccountManager.php:767
/home/runner/actions-runner/_work/server/server/lib/private/Accounts/AccountManager.php:810
/home/runner/actions-runner/_work/server/server/tests/lib/Accounts/AccountManagerTest.php:877

2. Test\Accounts\AccountManagerTest::testSanitizingFediverseServer with data set "valid response - no at" ('foo@example.com', 'foo@example.com', true, '{"username":"foo"}')
   InvalidArgumentException: fediverse

/home/runner/actions-runner/_work/server/server/lib/private/Accounts/AccountManager.php:767
/home/runner/actions-runner/_work/server/server/lib/private/Accounts/AccountManager.php:810
/home/runner/actions-runner/_work/server/server/tests/lib/Accounts/AccountManagerTest.php:877