Fix generic mime type being uploaded when several files are externally shared with the app. (#4715)

i.e. `image/*` when sharing a png and jpg file.

features/share/impl/src/main/kotlin/io/element/android/features/share/impl/ShareIntentHandler.kt

@@ -89,7 +89,7 @@ class DefaultShareIntentHandler @Inject constructor(
      * Use this function to retrieve files which are shared from another application or internally
      * by using android.intent.action.SEND or android.intent.action.SEND_MULTIPLE actions.
      */
-    private fun getIncomingUris(intent: Intent, type: String): List<ShareIntentHandler.UriToShare> {
+    private fun getIncomingUris(intent: Intent, fallbackMimeType: String): List<ShareIntentHandler.UriToShare> {
         val uriList = mutableListOf<Uri>()
         if (intent.action == Intent.ACTION_SEND) {
             IntentCompat.getParcelableExtra(intent, Intent.EXTRA_STREAM, Uri::class.java)
@@ -115,9 +115,12 @@ class DefaultShareIntentHandler @Inject constructor(
             }
         }
         return uriList.map { uri ->
+            // The value in fallbackMimeType can be wrong, especially if several uris were received
+            // in the same intent (i.e. 'image/*'). We need to check the mime type of each uri.
+            val mimeType = context.contentResolver.getType(uri) ?: fallbackMimeType
             ShareIntentHandler.UriToShare(
                 uri = uri,
-                mimeType = type
+                mimeType = mimeType,
             )
         }
     }