fix(client): fix type errors of Client's methods

[shuuji3]

This is my attempt to solve the existing type errors of client.ts in #60.

I merged main branch so it contains several commits (you can also update your branch), but the main changes are these two commits:

1. fd489cb - adjust typing of methods
2. 99d77dd - add placeholders for missing params (needs to be fixed later)

I thought the existing type errors have come from two issues:

• Using as for the record object, making the output type invalid.
  • So I tried to avoid using as, and also tried finding proper types from lexicon.ts and using OutputOf etc.
• Assigning type variable <Query> to Client in agent.ts.
  • I tried to keep <Query> but couldn't solve the type issue without removing it. But I feel like we could use Client without the type parameter. I'm not sure if this is the correct fix or not. This solution may be invalid if we need to keep <Query>. (feel free to dismiss in that case)