Frontend V2 Ui Tweaks (#4590)

* Top Controls only show when files > 0
* Moved content down so top controls don't obscure
* Viewer background set to match workbench and shadow around pages added
so that page boundaries are visible
* unsaved-changes modal rework

---------

Co-authored-by: Connor Yoh <[email protected]>

frontend/src/components/fileEditor/FileEditor.tsx

@@ -348,7 +348,7 @@ const FileEditor = ({
       <Box pos="relative" style={{ overflow: 'auto' }}>
         <LoadingOverlay visible={false} />
 
-        <Box p="md" pt="xl">
+        <Box p="md">
 
 
         {activeStirlingFileStubs.length === 0 && !zipExtractionProgress.isExtracting ? (
@@ -446,7 +446,7 @@ const FileEditor = ({
         onSelectFiles={handleLoadFromStorage}
       />
 
-      
+
       </Box>
     </Dropzone>
   );