refactor(AztecMacro): Remove all usages of Span::default()

[Maddiaa0]

Overview

To get the macros off the ground, I used Span::default() on all of the created types to prevent having to put the effort in to disclose where the macro was making errors.

As these macros have become more and more enshrined, removal of these default spans will help alot with tracking down bugs.

Links:

• aztec nr macros file: https://github.com/AztecProtocol/aztec-packages/blob/master/noir/aztec_macros/src/lib.rs