The function didn't check if `COPY_FILE_FAIL_IF_EXISTS` bit flag is set
or not, always failing if _any_ flags were set and the destination file
already existed.
This behavior was probably implemented under assumption that
`COPY_FILE_FAIL_IF_EXISTS` is the only valid flag, but it's not the case.
There are other flags, so this was breaking applications when they intend
to overwrite a file with e.g. `COPY_FILE_ALLOW_DECRYPTED_DESTINATION`.
These functions were affected by the problem:
- CopyFileEx - exposed by Total Commander not being able to overwrite file
- PrivCopyFileEx
- MoveFileWithProgress
Also cover `ERROR_ALREADY_EXISTS` returned by CreateFileW to match Windows
behavior, making the API tests pass.
CORE-10271