Revert the OIDC callback to use a custom scheme for now. (#1937)

Universal links are still slightly unreliable. We need to host a page at the redirect location so that if universal link detection fails we can fall back to opening the app using the scheme.

ElementX/Sources/Application/AppSettings.swift

@@ -134,13 +134,8 @@ final class AppSettings {
     
     /// Any pre-defined static client registrations for OIDC issuers.
     let oidcStaticRegistrations: [URL: String] = ["https://id.thirdroom.io/realms/thirdroom": "elementx"]
-    /// The redirect URL used for OIDC. The bundle ID suffix avoids app association conflicts between Element X, Nightly and PR builds.
-    let oidcRedirectURL = {
-        guard let bundleIDSuffix = InfoPlistReader.main.bundleIdentifier.split(separator: ".").last,
-              let redirectURL = URL(string: "https://mobile.element.io/oidc/\(bundleIDSuffix)")
-        else { fatalError("Failed creating a valid OIDC redirect URL.") }
-        return redirectURL
-    }()
+    /// The redirect URL used for OIDC.
+    let oidcRedirectURL: URL = "io.element:/callback"
 
     /// The date that the call to `/login` completed successfully. This is used to put
     /// a hard wall on the history of encrypted messages until we have key backup.

changelog.d/1936.bugfix

@@ -0,0 +1 @@
+Revert the OIDC redirect URL back to using a custom scheme.