Keep the in-progress edit when attaching media

Picking an attachment reset the composer to Normal, which dropped an
in-progress edit: the attachment went out as a new message and the
leftover edit text then created another one instead of editing the
original.

Route every attach path through a single resetComposerModeAfterAttaching()
helper that clears Reply/Normal but keeps an edit pending, so the typed
text still edits the original on the next send. This also covers the
multi-item gallery picker added in #6519, which reset the mode
unconditionally.

Reply is still cleared (the attachment becomes the reply).

Fixes #7083.

libraries/mediapickers/test/src/main/kotlin/io/element/android/libraries/mediapickers/test/FakePickerProvider.kt

@@ -19,6 +19,7 @@ import io.element.android.libraries.mediapickers.api.PickerProvider
 class FakePickerProvider : PickerProvider {
     private var mimeType = MimeTypes.Any
     private var result: Uri? = null
+    private var multipleResults: List<Uri>? = null
 
     @Composable
     override fun registerGalleryPicker(onResult: (uri: Uri?, mimeType: String?) -> Unit): PickerLauncher<PickVisualMediaRequest, Uri?> {
@@ -32,7 +33,7 @@ class FakePickerProvider : PickerProvider {
 
     @Composable
     override fun registerGalleryMultiPicker(onResult: (uris: List<Uri>) -> Unit): PickerLauncher<PickVisualMediaRequest, List<Uri>> {
-        return NoOpPickerLauncher { onResult(result?.let { listOf(it) } ?: emptyList()) }
+        return NoOpPickerLauncher { onResult(multipleResults ?: result?.let { listOf(it) } ?: emptyList()) }
     }
 
     @Composable
@@ -42,7 +43,7 @@ class FakePickerProvider : PickerProvider {
 
     @Composable
     override fun registerFileMultiPicker(mimeType: String, onResult: (uris: List<Uri>) -> Unit): PickerLauncher<Array<String>, List<Uri>> {
-        return NoOpPickerLauncher { onResult(result?.let { listOf(it) } ?: emptyList()) }
+        return NoOpPickerLauncher { onResult(multipleResults ?: result?.let { listOf(it) } ?: emptyList()) }
     }
 
     @Composable
@@ -59,6 +60,10 @@ class FakePickerProvider : PickerProvider {
         this.result = value
     }
 
+    fun givenMultipleResults(uris: List<Uri>) {
+        this.multipleResults = uris
+    }
+
     fun givenMimeType(mimeType: String) {
         this.mimeType = mimeType
     }