[feature request] Contract custom type definition generation support

[hychen]

Given a storage which has a custom type definition as below.

#[derive(....)]
struct CustomType {
    name: String
}

#[ink(storage)]
struct Store {
    members: ink_storage::collections::HashMap<AccountId, CustomType>
}

When a contract developer executes npx redspot compile. it generates three files as below

• artificats/store.contract :: the contract itself.
• artificats/store.json :: the contract metadata.
• artificats/store.ts.d :: the Typescript definiton of the custom types of the contract.(new)

So that a contract developer could import TS types to make ts-lint happy.

import { CustomType } from artificates.contract;
const contractFactory = await getContractFactory('contract', creator);
const contract = await contractFactory.deploy('new');
const member: CustomType = await contract.members(account_id).output;

Dependencies

• Generate type definitions for contract abi, just like generating type definitions for metadata (Generate type definitions for contract abi, just like generating type definitions for metadata. polkadot-js/api#3337)