Make RustMatrixClient.close asynchronous (#4513)

* Make `RustMatrixClient.close` asynchronous

This is a safer way to destroy the Rust instances associated to it. Since `MatrixClient` doesn't implement `Closeable` anymore, the method has been renamed to `destroy` to follow the existing naming in the project.

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/MatrixClient.kt

@@ -42,10 +42,9 @@ import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.flow.map
-import java.io.Closeable
 import java.util.Optional
 
-interface MatrixClient : Closeable {
+interface MatrixClient {
     val sessionId: SessionId
     val deviceId: DeviceId
     val userProfile: StateFlow<MatrixUser>