mmlid: Show a warning on LID web UI while piece doctor performing initial scan

[dirkmc]

When the user first migrates to boost v2.0, they will likely look at the LID page to see the new functionality.
The initial piece doctor scan takes 24 hours by default, so the LID page will show incomplete information.
We should show a warning to the user until the initial scan has completed:

Piece Doctor is performing an initial scan for pieces in LID, expected completion time: 14 hours