Add stargate msg

[ethanfrey]

Closes #694

Adds the message and the query types under a feature flag. And also add the proper requires export.

Contracts have it off by default and cargo test --features stargate passes in cosmwasm-std.

This is really just to pass info up to wasmd, and doesn't need test mocks (they would be too hard to build)

[webmaster128]

Looks good.

But if those messages don't go through signature verification, how is authorization checked (e.g. the MsgSend sender address)?

[webmaster128]

This is analogue to this call in CosmJS, right?

  public async queryUnverified(path: string, request: Uint8Array): Promise<Uint8Array> {
    const response = await this.tmClient.abciQuery({
      path: path,
      data: request,
      prove: false,
    });

    if (response.code) {
      throw new Error(`Query failed with (${response.code}): ${response.log}`);
    }

    return response.value;
  }

[ethanfrey]

Yes 💯 We can provide a link to that code which may help make it more clear

[webmaster128]

Good, thanks. Then we can avoid the term "message" here, right? It is just "request data" of any kind.

[ethanfrey]

But if those messages don't go through signature verification, how is authorization checked (e.g. the MsgSend sender address)?

This code handles redispatching the CosmosMsg returned from contracts.

Since we know who the caller is (the contract returning the message), we can easily enforce that is a valid signer, the same way they handle this in the sdk.

(This is done for all the messages, which is why we don't require sender fields on them - or auto-enforced the from_address of the BankMsg::Send)

[ethanfrey]

I think 8b7bc41 addresses all the comments.

[ethanfrey]

Any more changes required?

I will make another small PR on top of this now.