[App] Implement more floating point operations in modules/

We've been building up verified IEEE FP32 operations (and also some bf16 operations); e.g.

* fpadd, fpmul in https://github.com/google/xls/tree/6e21d521d32fd484690664d81309631f07edab55/xls/modules
* bf16 "next float" style significand bumping: https://github.com/google/xls/blob/1b6859dc384fe8fa39fb901af3de8453661ff345/xls/dslx/stdlib/bfloat16.x#L29

It would be interesting to comb through the IEEE FP32 specification and implement some more of the primitive operations.

/cc @majnemer if there are any particularly interesting ones you might recommend