fix(rpc-types): accept Address in to builder method for TxReq

[yash-atreya]

Motivation

The to builder method for TransactionRequest takes Option<Address> as arg. This is inconsistent with other builder methods.

Solution

Use Address type for arg and wrap it in Some inside the method

PR Checklist

• Added Tests
• Added Documentation
• Breaking changes

[DaniPopes]

to is different because an empty to address is a contract creation no?

[mattsse]

this makes it consistent with the other setters

[mattsse]

to is different because an empty to address is a contract creation no?

yeah but the builder starts out with None, imo this is the right choice because this is also how the other setters work

[prestwich]

not convinced we should default to create instead of erroring if not specifically set to create, as creating with value and empty data is a valid tx that burns user funds. We should probably error on building if to is unset, and provide a shortcut for .create()

[prestwich]

i.e. this behavior would burn funds

let mut builder = Default::default().with_value(1 ether);
provider.send_transaction(
   builder
).await;