Enhance type definition

https://github.com/CodeChain-io/codechain-rpc-js/blob/adcec954c3bab00cd1893a412afcdad500297395/src/chain.ts#L4-L8
Many types are merely an alias of Object.

Start with src/chain.ts lines 4-8, then trace where the aliased Object types are used in the RPC wrapper. Identify the intended shape of each affected value and replace the aliases with specific TypeScript definitions; done means the types no longer use generic Object aliases without breaking the package.

由索引模型根据 Issue 内容生成。