Fix dialog styles, remove context menu from ConversationListItem's dialogs

- Restore dialog styles that magically disappeared
- Fix font-family on ConfirmationDialog's content
- Remove the custom context menu that was appearing on dialogs

Change-Id: If828d5f6b3bdfc2a6e31c58fe40ad5fff286df3d
diff --git a/client/src/components/Dialog.tsx b/client/src/components/Dialog.tsx
index 9a6790d..aa9f01c 100644
--- a/client/src/components/Dialog.tsx
+++ b/client/src/components/Dialog.tsx
@@ -100,6 +100,7 @@
 interface ConfirmationDialogProps extends Omit<BaseDialogProps, 'actions'> {
   onConfirm: () => void;
   confirmButtonText: string;
+  content: string;
 }
 
 export const ConfirmationDialog = ({ onConfirm, confirmButtonText, ...props }: ConfirmationDialogProps) => {
@@ -109,6 +110,7 @@
   return (
     <BaseDialog
       {...props}
+      content={<Typography variant="body1">{props.content}</Typography>}
       actions={
         <>
           <Button onClick={onConfirm}>{confirmButtonText}</Button>