Notify user when DF logs have been cleared

I like the fact that MP gives status bar and chime upon completion for downloading DF logs. Would it be possible to also give status bar and chime upon completion when clearing logs? Otherwise we're left wondering, and without pulling SD card (embedded within build) we won't know for sure that partial or complete clearing was successful.

Kelly

Start by tracing the existing DF-log download completion path in Mission Planner and locating the corresponding clear-logs flow. Reuse the established status-bar and chime behavior for clear-log completion, then verify that users receive confirmation after clearing logs without removing the SD card.

Written by the indexing model from the issue text.