fix(auth, android): do not timezone offset when getting UTC timestamp (#4886)

* Add test for expirationTime of tokenResult
* Fix android timestampToUTC util
* Use single quote

Author: kouheiszk

packages/app/android/src/reactnative/java/io/invertase/firebase/common/SharedUtils.java

@@ -97,12 +97,10 @@ public static WritableMap getExceptionMap(Exception exception) {
   }
 
   public static String timestampToUTC(long timestamp) {
-    Calendar calendar = Calendar.getInstance();
     long millisTimestamp = timestamp * 1000;
-    Date date = new Date(millisTimestamp + calendar.getTimeZone().getOffset(millisTimestamp));
-    SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.US);
+    SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
     format.setTimeZone(TimeZone.getTimeZone("UTC"));
-    return format.format(date);
+    return format.format(millisTimestamp);
   }
 
   /**

packages/auth/e2e/user.e2e.js

@@ -71,8 +71,12 @@ describe('auth().currentUser', function () {
 
       tokenResult.claims.should.be.a.Object();
       tokenResult.claims.iat.should.be.a.Number();
+      tokenResult.claims.exp.should.be.a.Number();
       tokenResult.claims.iss.should.be.a.String();
 
+      new Date(tokenResult.issuedAtTime).getTime().should.equal(tokenResult.claims.iat * 1000);
+      new Date(tokenResult.expirationTime).getTime().should.equal(tokenResult.claims.exp * 1000);
+
       tokenResult.signInProvider.should.equal('password');
       tokenResult.token.length.should.be.greaterThan(24);