refactor contract calls: convenience methods in SDK and SophiaTypes in SDK

[marc0olo]

I was thinking about how to improve pure SDK usage for contract calls and I think the JS-SDK is doing this quite will right now. it is converting the Sophia types.

Example calls that should be possible using the SDK:

• deploy(txOptions: ContractTxOptions)
• call(contractId: String, entrypoint: String, txOptions: ContractTxOptions) (for stateful and payable calls)
• callReadOnly(contractId: String, entrypoint: String) (for read-only dry-run calls)

I see following tasks in this issue:

• use the new convenience methods in the SDK
• use SophiaType classes of the SDK wherever it's possible and makes sense

[marc0olo]

I started type integration in the sdk with kryptokrauts/aepp-sdk-java#211

there are now convenience methods in the SDK for contract creation and regular stateful calls where a ContractTxOptions object can be passed to that can contain different params.

for read-only (dry-run) calls there is also a specific convenience method in the SDK now where we don't need any additional params as we always use the zero-address in those read-only dry-runs.