Need automated way to reset kbfs

There needs to be a way of resetting a KBFS directory which doesn't involve asking someone here for help. Ideally, the resetting of KBFS should be automated via our credentials such as PGP key when we no longer have access to any devices or have already revoked them, similarly to how we can reset the entire account.

My personal situation is that I revoked all my previous devices because I overwrote their OS with clean installations. It did not occur to me that I wouldn't be able to access _some_ of Keybase functionality when other functions are still usable via my PGP key.

BEGIN KEYBASE SALTPACK SIGNED MESSAGE. kXR7VktZdyH7rvq v5wcIkHbs8cbs72 tAUySI4VfwQsYeR uwYqXCO39lpVvM4 k3sfF6zQdP4JKSP vArNveHmBeMSDxy WaALhC96XYlPswB IC4NZ2mOiRXBacT Tyi9V1MXV21ef3c 8w937gKtY59HfRX gmL7ESvtFwYLjJL bMAFJNA9GBKiRcd hA8V7VvLUQHhKwk CHVES1dzyjUWsKr rJ21M7dBpUUzRug VNcyD3ChYjI9yXp hIm1QNvJpl5AlYV cY4BFALhhW2kpUx ZlCVqWlmWq5OSCC 2oxO6zhsYZrNaMU KQBdEfHpUXny57i Ga5wf5CW6ZOSgLy 084H8y09XBla69R 8eRBoYh0ma873Me c0cBFhfLamyNZNw BxcOe3dTRYQOFD3 pt2iVBkizopABfx UkEGSN9oVawr5gi sWXstsv6Q4kq6R5 DrDRFkS3PgSai9F JKqzxx4rWwtADEx PP45v5Qp028OW. END KEYBASE SALTPACK SIGNED MESSAGE.

No source file, test, or entry point is named in the issue. Start by locating the KBFS reset flow and the existing whole-account reset path, then define how PGP credentials should work after all devices are revoked. Done should include an automated reset path and coverage for the no-device scenario.

Written by the indexing model from the issue text.