winmm: Implement support for querying the names for open mci devices

The patch implements the code for mci_sysinfo with mci_sysinfo_name | mci_sysinfo_open flags,
which allows applications to retrieve the name of open mci devices.

While at it, in MCI_FinishOpen, check the result of HeapAlloc and return an appropriate error
if it fails. In MCI_UnLoadMciDriver, check for NULL pointer before calling HeapFree.