pull_adb_file derived its host file name from the last path segment of a
caller-supplied device path and joined it to the output directory without
checking that the name is usable on the host. A device path ending in a
separator, a dot segment, a control character, a Windows reserved device
name, a trailing dot or space, or a ':' alternate-data-stream marker could
resolve to an unexpected host path or fail opaquely after the transfer.
The single-file path now derives the name with POSIX semantics and refuses
any non-portable segment as invalid_request before creating a directory or
running adb pull. This matches the package path's pending host-name policy
and never renames a device-reported file.
Co-authored-by: morluto <[email protected]>
