zkProofs slow speed in 32 bits architecture

[ed255]

zkProofs operations are slow on 32 bits architecture: iden3/go-circom-prover-verifier#23

This affects:

• Holder: generating ownership zk proof
• ZkFiles: Loading proving key

On 32 bits archs these operations are around 40 times slower.

Since a few years ago most of the new mobile phones are 64 bit ARM architecture, so in theory only old devices would be affected.

This also could affect Android emulation: if x86 emulation is used, the performance of zk proof functionality will be very poor (we already experienced this in firebase where tests timed out when running on an x86 Android emulator).