HPCC-9450 ECL Watch should warn about files sizes being larger than 4GB

Add a dialog message warning user regarding uploading file(s) in excess of 4GB due to the browsers limitation.

Signed-off by <miguel.vazquez@lexisnexis.com>
Can you replace this with an IF, while there is nothing wrong with this code, the use of "?" is typically used for the "one liner" operations: a = b > c ? b : c;
Also I tend to avoid "side effects" within b + c above (functions which change values etc.).