ApInt used for IntegerAttr is not production ready

[vaivaswatha]

To implement IntegerAttr, the ApInt library is used, but this library is not production ready. Find an alternate or contribute to ApInt.

Note that other arbitrary fixed with integer implementations, such as crypto-bigint or bnumm require the fixed width to be known at compile time, while others such as num-bigint are dynamic width integers. Only ApInt provides runtime arbitrary fixed-width integers, same as LLVM's APInt.

This one seems like a good candidate: https://docs.rs/awint/0.9.0/awint/awi/struct.ExtAwi.html