Make cookie consent component not to receive mouse events when closed (…

…#1177)

**Related Ticket:** #953 

### Description of Changes
Make cookie consent component not to receive mouse events when closed.

### Notes & Questions About Changes
This might be able to be resolved with #1170 , but here is a quick fix.


### Validation / Testing
Go to
https://veda-ui.netlify.app/exploration?datasets=%5B%5D&taxonomy=%7B%7D
, close cookie consent form and try to add datasets. The button click is
blocked because we are hiding the component only with opacity. (And
check the same work flow on this PR's preview)

app/scripts/components/common/cookie-consent/index.scss

@@ -1,3 +1,7 @@
 .animation--fade-out {
   transition: opacity 0.5s ease-in-out 0.125s;
 }
+
+.pointer-events--none {
+  pointer-events: none;
+}

app/scripts/components/common/cookie-consent/index.tsx

@@ -57,7 +57,7 @@ export const CookieConsent = ({
     <div
       id='cookie-consent'
       className={`margin-0 tablet:margin-2 shadow-2 position-fixed z-top maxw-full tablet:maxw-tablet-lg animation--fade-out right-0 bottom-0 ${
-        cookieConsentResponded || closeConsent ? ' opacity-0' : 'opacity-1'
+        cookieConsentResponded || closeConsent ? ' opacity-0 z-bottom pointer-events--none' : 'opacity-1 z-top'
       }`}
     >
       <USWDSAlert