[bugfix] Use punycode for host part of resource query param when doing webfinger requests

[tsmethurst]

Description

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This pull request fixes an issue where we were using url-escaped unicode for account domains in webfinger queries. According to the webfinger RFC, the resource value must be a valid URI, and according to the URI RFC, the host part of a URI must contain only ASCII (I know, I know...).

To support this change, the check for dereferenced final account / status URIs has been updated to account for passing in unicode search queries, as otherwise the status or account will be rejected.

Checklist

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[tsmethurst]

Ah hang on, found one thing that still needs to change.

Hang that, I'll put it in a separate PR.

[tsmethurst]

I'm gonna squerge this one for now cuz I think it's fairly uncontroversial and fixes an immediate issue.

In a follow-up PR I wanna update the GetAccountByURI, GetAccountByURL, GetStatusByURI, and GetStatusByURL functions to also check in the database for both punycoded and unicoded URIs (preferring punycoded), but that doesn't belong here.

[tsmethurst]

I think future work could also add a wrapper around punify to use a TTL cache holding a map of punicode vs unicode domains, just to prevent repeated operations on the same host values, but I can do this in a separate PR too.