refactor(crypto): Create a MSC and intent specific accessor for the QR login data type

This patch adds a view into the MSC-specific and intent specific data
fields of the QR login data type.

MSC4108 and MSC4388 have subtle differences in the way the rendezvous
URL and the server name are shared, this new getter allows us to access
all of those fields in a consistent manner.

MSC4108: https://github.com/matrix-org/matrix-spec-proposals/pull/4108
MSC4388: https://github.com/matrix-org/matrix-spec-proposals/pull/4388

examples/qr-login/src/main.rs

@@ -6,7 +6,7 @@ use futures_util::StreamExt;
 use matrix_sdk::{
     Client,
     authentication::oauth::{
-        qrcode::{LoginProgress, QrCodeData, QrCodeIntentData, QrProgress},
+        qrcode::{LoginProgress, Msc4108IntentData, QrCodeData, QrCodeIntentData, QrProgress},
         registration::{ApplicationType, ClientMetadata, Localized, OAuthGrantType},
     },
     ruma::serde::Raw,
@@ -101,7 +101,9 @@ async fn login(proxy: Option<Url>) -> Result<()> {
 
     let data = QrCodeData::from_base64(input).context("Couldn't parse the base64 QR code data")?;
 
-    let QrCoodeIntentData::Reciprocate { server_name } = &data.intent_data() else {
+    let QrCodeIntentData::Msc4108 { data: Msc4108IntentData::Reciprocate { server_name }, .. } =
+        &data.intent_data()
+    else {
         bail!("The QR code is invalid, we did not receive a homeserver in the QR code.");
     };
     let mut client = Client::builder().server_name_or_homeserver_url(server_name);