Rebuild ics23 proofs with ts-proto for cosmjs compatibility

[ethanfrey]

I think it is just about T | null | undefined vs T | undefined.

This is the compile error I got trying it.

Type 'IProofSpec' is not assignable to type '{ leafSpec?: { hash?: HashOp | undefined; prehashKey?: HashOp | undefined; prehashValue?: HashOp | undefined; length?: LengthOp | undefined; prefix?: Uint8Array | undefined; } | undefined; innerSpec?: { ...; } | undefined; maxDepth?: number | undefined; minDepth?: number | undefined; }'.
  Types of property 'leafSpec' are incompatible.
    Type 'ILeafOp | null | undefined' is not assignable to type '{ hash?: HashOp | undefined; prehashKey?: HashOp | undefined; prehashValue?: HashOp | undefined; length?: LengthOp | undefined; prefix?: Uint8Array | undefined; } | undefined'.
      Type 'null' is not assignable to type '{ hash?: HashOp | undefined; prehashKey?: HashOp | undefined; prehashValue?: HashOp | undefined; length?: LengthOp | undefined; prefix?: Uint8Array | undefined; } | undefined'.

176     proofSpecs: [iavlSpec, tendermintSpec],

[crodriguezvega]

I will close the issue, since we removed the Typescript implementation.