Don't leak MediaFileHandle when downloading voice messages (#1748)

Uses the new `MediaFile.persist()` [API](https://github.com/matrix-org/matrix-rust-sdk/pull/2789) to cache voice messages.
This allows to close the `MediaFile` handle after use and keeping the file.
Also disables rust sdk caching for voice messages as we'll use the app's cache dir for that purpose.

Fixes: https://github.com/vector-im/element-meta/issues/2175

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/media/RustMediaFile.kt

@@ -25,6 +25,10 @@ class RustMediaFile(private val inner: MediaFileHandle) : MediaFile {
         return inner.path()
     }
 
+    override fun persist(path: String): Boolean {
+        return inner.persist(path)
+    }
+
     override fun close() {
         inner.close()
     }

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/media/RustMediaLoader.kt

@@ -71,7 +71,12 @@ class RustMediaLoader(
             }
         }
 
-    override suspend fun downloadMediaFile(source: MediaSource, mimeType: String?, body: String?): Result<MediaFile> =
+    override suspend fun downloadMediaFile(
+        source: MediaSource,
+        mimeType: String?,
+        body: String?,
+        useCache: Boolean,
+    ): Result<MediaFile> =
         withContext(mediaDispatcher) {
             runCatching {
                 source.toRustMediaSource().use { mediaSource ->
@@ -79,7 +84,7 @@ class RustMediaLoader(
                         mediaSource = mediaSource,
                         body = body,
                         mimeType = mimeType ?: MimeTypes.OctetStream,
-                        useCache = true,
+                        useCache = useCache,
                         tempDir = cacheDirectory.path,
                     )
                     RustMediaFile(mediaFile)