[KERNEL32] BasepCopyFileExW: Check dwCopyFlags properly (reactos#9133)

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

Author: xmine64

dll/win32/kernel32/client/file/copy.c

@@ -254,11 +254,13 @@ BasepCopyFileExW(IN LPCWSTR lpExistingFileName,
                                              GENERIC_WRITE,
                                              FILE_SHARE_WRITE,
                                              NULL,
-                                             dwCopyFlags ? CREATE_NEW : CREATE_ALWAYS,
+                                             (dwCopyFlags & COPY_FILE_FAIL_IF_EXISTS) ? CREATE_NEW : CREATE_ALWAYS,
                                              FileBasic.FileAttributes,
                                              NULL);
                 if (INVALID_HANDLE_VALUE != FileHandleDest)
                 {
+                    if (!(dwCopyFlags & COPY_FILE_FAIL_IF_EXISTS) && GetLastError() == ERROR_ALREADY_EXISTS)
+                        SetLastError(ERROR_SUCCESS);
                     errCode = CopyLoop(FileHandleSource,
                                        FileHandleDest,
                                        FileStandard.EndOfFile,