add /openid/request_token and /openid/userinfo routes

heavily changed and improved by me

Co-authored-by: mikoto <avdb@keemail.me>
Signed-off-by: strawberry <strawberry@puppygock.gay>

src/service/users/mod.rs

@@ -477,6 +477,15 @@ impl Service {
 	pub fn get_filter(&self, user_id: &UserId, filter_id: &str) -> Result<Option<FilterDefinition>> {
 		self.db.get_filter(user_id, filter_id)
 	}
+
+	/// Creates an OpenID token, which can be used to prove that a user has
+	/// access to an account (primarily for integrations)
+	pub fn create_openid_token(&self, user_id: &UserId, token: &str) -> Result<u64> {
+		self.db.create_openid_token(user_id, token)
+	}
+
+	/// Find out which user an OpenID access token belongs to.
+	pub fn find_from_openid_token(&self, token: &str) -> Result<OwnedUserId> { self.db.find_from_openid_token(token) }
 }
 
 /// Ensure that a user only sees signatures from themselves and the target user