[Proposal] Profiling in snarkvm-fields should be optional

[MauroToscano]

💥 Proposal

aleo-std crate is used for profiling in snarkvm-fields. This crate and its invocations should be enabled with an independent feature.

fields/src/traits/poseidon_default.rs is the only file on snarkvm-fields using this crate for profiling

The uses of end_timer and start_timer can be wrapped with a cfg feature enabled as needed