Add page to request execution using an execution token and some execution parameters

[longtomjr]

• Request attestation with the exec_enclave exec/attest
• Add a field to paste in an execution token
• Encrypt the execution token with the exec_enclave's public key and a local ephemeral private key (use existing box functions)
• Send the encrypted token + some execution parameters to /exec/request
• Display the result from the execution (or poll an endpoint to display the status and then the result when ready) -> see: Add endpoint to request execution for a given token rtc-data#71