feat(ffi): expose append parameter on Client::set_pusher

Forwards the new SDK append flag across the FFI boundary so multi-profile
clients can register pushers without overwriting each other.

Breaking change: Client::set_pusher now takes an append: bool parameter.

Signed-off-by: Daniel Anderson <daniel.anderson@toptal.com>

Author: danderson-cont

bindings/matrix-sdk-ffi/changelog.d/6600.changed.md

@@ -0,0 +1 @@
+[**breaking**] `Client::set_pusher` now takes an `append: bool` parameter, forwarded to the homeserver. Pass `true` to keep an existing pusher with the same `app_id` and `pushkey` registered for other users (e.g. multi-profile clients on a single device); pass `false` to preserve the previous default behaviour.

bindings/matrix-sdk-ffi/src/client.rs

@@ -1477,6 +1477,7 @@ impl Client {
         device_display_name: String,
         profile_tag: Option<String>,
         lang: String,
+        append: bool,
     ) -> Result<(), ClientError> {
         let ids = identifiers.into();
 
@@ -1488,7 +1489,7 @@ impl Client {
             profile_tag,
             lang,
         };
-        self.inner.pusher().set(pusher_init.into(), false).await?;
+        self.inner.pusher().set(pusher_init.into(), append).await?;
         Ok(())
     }