Great idea, must have !

I needed that in RB so many times but ended up doing it in Reaper, just do the ACW then
just write the metronome to a midi track, drag export midi track to Reaper then drag in the original audio.
Then I use Stretch Makers to Quantize the audio.
1. Set Project Tempo.
2. Grouped all tracks if more than 1 like drums.
3. Actions > Show Action List > New > Create an Action Hotkey to move to "Go forward one beat"
and "Item: Add stretch maker at current position" then Shortcuts for selected action > Add.
4. View > show Master Track.
5. Right click on Tempo points > select all
6. Right click on Tempo points > reset points to zero/center
7. Highlight track/s from start to end.
5. Item > Stretch markers > Snap Stretch Markers within time selection to grid.

Back to RB, remove the tempo map, just set the constant tempo and drag the Quantized audio rendered from Reaper into RB.