Proof of Place for BTC Map.

Where BTC Map would Attest that a given Place had been verified out-of-band (i.e. we checked the npub was actually in control of the property claimed).

More detail on Proof-of-Place and Attestations more generally here:

https://docs.google.com/presentation/d/11RcCs25ziANe_THKTyvrDEgwhY6lqByqdtcYr9efKtY/edit?slide=id.g33d12993bf5_0_262#slide=id.g33d12993bf5_0_262