[x/stableswap][osmomath] Increase precision of osmomath BigDec to 36 prevent stableswap CFMM precision issues

[AlpinYukseloglu]

Background

The current BigDec precision significantly limits the use of our current stableswap CFMM. There are a number of ways we can tackle this, but the cleanest path is likely to just increase our BigDec precision bounds. This would also have the added benefit of making our binary search CFMM solver viable, drastically reducing the amount of computation spent on invariant calculations.

Suggested Design

• Increase BigDec bit length to 1024 (to accommodate large k values)
• Increase BigDec decimal precision to 36

Acceptance Criteria

• All existing and new tests should pass