cosmic-proto toProtoMsg relying on Decimal fail

[turadg]

Describe the bug

We have a patch for @cosmjs/math to eschew bn.js, which is huge and doesn't play well with SES.

It has multiple problems.

To Reproduce

Use ibc-mocks.ts to make a call like,

buildQueryResponseString(
        QueryDelegatorDelegationsResponse,
        {
          delegationResponses: [
            {
              delegation: {
                delegatorAddress: 'cosmos1test',
                validatorAddress: mockValidator.value,
                shares: '1000000',
              },
              balance: { denom: 'uatom', amount: '1000000' },
            },
          ],
        },
      )

shares is parsed as a Decimal but that's currently broken. It errors with 'Fewer than two elements in split result. This must not happen here.'. That's because the patch does .search(/./') when it should be.search(/\./') (lost in the .patch creation).

After fixing that is a deeper error at this line in staking.ts,

.string(Decimal.fromUserInput(message.sharesDst, 18).atomics)

Our version of the Decimal object doesn't have atomics so that fails. In the real one atomics is a BN.js object, which we're trying to avoid.

Expected behavior

Constructing a QueryDelegatorDelegationsResponse works.

Platform Environment

@endo/init@1.1.4
ses@1.8.0

Additional context

We've run into hurdles before,

• decode delegation query response fails in Compartment due to undefined Decimal #9408

Ideally we could use cosmjs without bn.js,

• Remove bn.js dependency from @cosmjs/math cosmos/cosmjs#203