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 <miguel.vazquez@lexisnexis.com>
Merge pull request #5986 from miguelvazq/HPCC-9450

HPCC-9450 ECL Watch should warn about files sizes being larger than 4GB

Reviewed-By: Gordon Smith <gordon.smith@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>