Feature Request: Add simulateTransaction and sendTransaction helper methods

[piyalbasu]

It would be nice to abstract the simulateTransaction and sendTransaction workflows to simplify the dev experience. There is a nice attempt at this in the soroban-react repo (https://github.com/esteblock/soroban-react/tree/main/packages/contracts/src), but in my opinion, these helpers would be more useful separated from React concerns and handled by this library.

Engineers looking to add to existing Stellar projects as well as those starting from scratch will likely want access to these helper methods while not being strictly tied to the design patterns offered by soroban-react