Fix file:copy to return error when target file exists without REPLACE_EXISTING#577

DharshiBalasubramaniyam wants to merge 4 commits intoballerina-platform:masterballerina-platform/module-ballerina-file:masterfrom

DharshiBalasubramaniyam:file-copy-replace-false-fixDharshiBalasubramaniyam/module-ballerina-file:file-copy-replace-false-fixCopy head branch name to clipboard