Add button to copy mnemonic after creating new wallet (#9)

Part of [laconicd testnet validator enrollment](https://www.notion.so/laconicd-testnet-validator-enrollment-6fc1d3cafcc64fef8c5ed3affa27c675)

Co-authored-by: IshaVenikar <ishavenikar7@gmail.com>
Reviewed-on: cerc-io/laconic-wallet-web#9

src/components/Dialog.tsx

@@ -5,10 +5,13 @@ import styles from '../styles/stylesheet';
 import GridView from './Grid';
 import { CustomDialogProps } from '../types';
 
-
 const DialogComponent = ({ visible, hideDialog, contentText }: CustomDialogProps) => {
   const words = contentText.split(' ');
 
+  const copyMnemonic = () => {
+    navigator.clipboard.writeText(contentText)
+  };
+
   return (
     <Dialog open={visible} onClose={hideDialog}>
       <DialogTitle>Mnemonic</DialogTitle>
@@ -22,6 +25,7 @@ const DialogComponent = ({ visible, hideDialog, contentText }: CustomDialogProps
         <GridView words={words} />
       </DialogContent>
       <DialogActions>
+        <Button onClick={copyMnemonic}>Copy</Button>
         <Button onClick={hideDialog}>Done</Button>
       </DialogActions>
     </Dialog>