refactor: Implement avatar image viewer and adjust design

Signed-off-by: Krille <c.kussowski@famedly.com>

lib/widgets/mxc_image_viewer.dart

@@ -0,0 +1,60 @@
+import 'package:flutter/material.dart';
+
+import 'package:flutter_gen/gen_l10n/l10n.dart';
+
+import 'mxc_image.dart';
+
+class MxcImageViewer extends StatelessWidget {
+  final Uri mxContent;
+
+  const MxcImageViewer(this.mxContent, {super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final iconButtonStyle = IconButton.styleFrom(
+      backgroundColor: Colors.black.withAlpha(200),
+      foregroundColor: Colors.white,
+    );
+    return GestureDetector(
+      onTap: () => Navigator.of(context).pop(),
+      child: Scaffold(
+        backgroundColor: Colors.black.withAlpha(128),
+        extendBodyBehindAppBar: true,
+        appBar: AppBar(
+          elevation: 0,
+          leading: IconButton(
+            style: iconButtonStyle,
+            icon: const Icon(Icons.close),
+            onPressed: Navigator.of(context).pop,
+            color: Colors.white,
+            tooltip: L10n.of(context).close,
+          ),
+          backgroundColor: Colors.transparent,
+        ),
+        body: InteractiveViewer(
+          minScale: 1.0,
+          maxScale: 10.0,
+          onInteractionEnd: (endDetails) {
+            if (endDetails.velocity.pixelsPerSecond.dy >
+                MediaQuery.of(context).size.height * 1.5) {
+              Navigator.of(context, rootNavigator: false).pop();
+            }
+          },
+          child: Center(
+            child: GestureDetector(
+              // Ignore taps to not go back here:
+              onTap: () {},
+              child: MxcImage(
+                key: ValueKey(mxContent.toString()),
+                uri: mxContent,
+                fit: BoxFit.contain,
+                isThumbnail: false,
+                animated: true,
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+}