feat: add solid border for contrast (#7550)

Now it is better to see the command bar.


![image](https://github.com/Unleash/unleash/assets/964450/a59bdabd-5a14-45a5-b8ca-594b62853c59)

frontend/src/component/commandBar/CommandBar.tsx

@@ -43,6 +43,7 @@ export const CommandResultsPaper = styled(Paper)(({ theme }) => ({
     fontSize: theme.fontSizes.smallBody,
     color: theme.palette.text.secondary,
     wordBreak: 'break-word',
+    border: `1px solid ${theme.palette.neutral.border}`,
 }));
 
 const StyledContainer = styled('div', {