Decide whether to keep V1 eth_send_transaction and sol_send_transaction methods #24

After #20 the Python client exposes only the V2 send transaction methods. EthSendTransactionBody now takes calls and SolSendTransactionBody takes signWiths. The TypeScript SDK keeps the V1 methods next to the V2 ones.

Follow-up: decide whether Python needs V1 methods for compatibility. If yes, teach the generator to emit versioned method names for activities that have more than one live version. If no, say so in the #20 changelog and mark the change as breaking.

Depends on #20.