fix: elevate remove attachment preview button to allow removal of failed upload attachments (#333)

Author: MartinCupela

src/v2/styles/AttachmentPreviewList/AttachmentPreviewList-layout.scss

@@ -114,7 +114,7 @@
     top: calc(var(--str-chat__spacing-px) * 2);
     inset-inline-end: calc(var(--str-chat__spacing-px) * 2);
     cursor: pointer;
-    z-index: 0;
+    z-index: 1;
 
     svg {
       width: calc(var(--str-chat__spacing-px) * 24);