Implement profile API

[VyrCossont]

Description

This Mastodon 4.2 extension provides capabilities missing from the existing Mastodon account update API: deleting an account's avatar or header.

See: https://docs.joinmastodon.org/methods/profile/ and #823

Review notes

This is really an extension of the account API, not a new thing, so I've added it to the account processor. That required the account processor to take a dependency on the media processor as well as the media manager (since the media manager doesn't have the delete-attachment-by-ID functionality we need).

The two new endpoints have nearly identical logic except for which attachment they affect (avatar or header).

Checklist

• I/we have read the GoToSocial contribution guidelines.
• I/we have discussed the proposed changes already, either in an issue on the repository, or in the Matrix chat.
• I/we have not leveraged AI to create the proposed changes.
• I/we have performed a self-review of added code.
• I/we have written code that is legible and maintainable by others.
• I/we have commented the added code, particularly in hard-to-understand areas.
• I/we have made any necessary changes to documentation.
• I/we have added tests that cover new code.
• I/we have run tests and they pass locally with the changes.
• I/we have run go fmt ./... and golangci-lint run.

[tsmethurst]

The dependency stuff feels a bit convoluted, I wonder if it would be good enough to just update the header/avatar media attachment IDs on the account and then let the media cleanup do the actual deletion of the media from storage later on when it does cleanup? I'll double check this when we're back from holiday.

[VyrCossont]

Alternatively, we could move account.Processor.deleteProfileAttachment into media.Processor itself. It's sort of on the line between media and accounts, and could fit into either processor.

I'd rather delete the deleted avatar/header media immediately, as that's what the media processor already does when deleting a regular media attachment. The user might expect this in the case of something like uploading the wrong file.