Load Field types from calldata lazily in brillig

[TomAFrench]

Currently during brillig codegen we always immediately copy all of the arguments out of calldata and into memory.

https://github.com/noir-lang/noir/blob/master/compiler/noirc_evaluator/src/brillig/brillig_ir/entry_point.rs#L152-L184

This works but is a bit wasteful as we can read these values from calldata at any time. One optimization we could then do is have any reference to a Field type argument load this directly from calldata when needed rather than preemptively loading it into memory.