Convert consts to field elements from u32 if possible

If we know that a constant value is smaller than u32 we should try to use conversions from u32. For example: E::from(2_u32) instead of E::from(2_u64) as we may come up with a more efficient reduction for smaller values later on.

_Originally posted by @bobbinth in https://github.com/0xPolygonMiden/air-script/pull/58#discussion_r1022350246_