Fix OpenUserProfile links having multiple argument types

[frenzibyte]

• See Add context menu and copy support for URL-based hyperlink text #23334 (comment) and Add context menu and copy support for URL-based hyperlink text #23334 (comment)

OpenUserProfile having more than one argument type makes it hard to retrieve the URL from LinkDetails as done in the PR linked above, and generally convolutes the process of handling OpenUserProfile basically anywhere.

Besides that, LinkDetails having arguments of type object is already bad on its own, but the whole structure is bad anyway.

[peppy]

I'm not sure this is achieving much. I guess you're trying to box everything into "can be shoved in URL", but that's not the case. Usernames need to be prefixed with an @ going forward (see ppy/osu-web#10303).

Probably want an extension method (or just property) on IUser to generate the URL, and then make everything use IUser instead?

[frenzibyte]

The idea of this PR is more of trying to use one simple type for LinkDetails arguments (right now on OpenUserProfile there are shockingly two types and multiple ways to handle the link appropriately, 1. handle IUser with only username, 2. handle IUser with online ID and invalid username, 3. handle string).

With the PRs you linked above, I'll imagine us just updating the LinkDetails construction of opening user profiles to append a @ when dealing with a username.

[frenzibyte]

I guess I wouldn't mind changing the argument type to IUser as long as the handling is still in place.