Do not draw the media loading progress bar under the status bar

The media viewer is edge to edge and the loading progress indicator was the
top-most child of a container that only applied navigation bar padding, so it
was laid out at y=0, behind the status bar and any display cutout.

Give it safeDrawing horizontal and top padding, reusing the idiom already used
by MediaViewerBottomBar in the same file. The inset deliberately does not come
from the scaffold content padding, which collapses to zero when the user taps
to hide the overlay.

libraries/mediaviewer/impl/src/main/kotlin/io/element/android/libraries/mediaviewer/impl/viewer/MediaViewerView.kt

@@ -414,6 +414,7 @@ private fun MediaViewerPage(
             if (showProgress) {
                 LinearProgressIndicator(
                     modifier = Modifier
+                        .padding(WindowInsets.safeDrawing.only(WindowInsetsSides.Horizontal + WindowInsetsSides.Top).asPaddingValues())
                         .fillMaxWidth()
                         .height(2.dp)
                 )