Add TransactionBuilder.setFootprint() method to prepare footprint easily

[Shaptic]

This is much better than creating an entire, mostly-empty xdr.SorobanTransactionData and using setSorobanData() when you want to create a bump or restore operation.

[github-actions]

Size Change: +30.1 kB (+1%)

Total Size: 3.01 MB

Filename	Size	Change
dist/stellar-base.js	2.21 MB	+22.6 kB (+1%)
dist/stellar-base.min.js	800 kB	+7.56 kB (+1%)

_{compressed-size-action}

[aristidesstaffieri]

so for my use case I think I needed to keep the rest of the resources, so I set it like this

const sorobanTxData = xdr.SorobanTransactionData.fromXDR(
    simulation.transactionData,
    "base64",
  );
  sorobanTxData.resources().footprint(footprint);
  txnBuilder.setSorobanData(sorobanTxData);

so basically I merged a new simulation's resources with an old footprint, would I still be able to do that if sorobanDataFromFootprint 0s out the other keys of the SorobanResources?

[Shaptic]

yeah so you wouldn't want to use these. instead, you'd want this:

txnBuilder
  .setSorobanData(sorobanTxData)
  .setFootprint(footprint.readOnly(), footprint.readWrite());

for this: the latter call will leave the existing fields alone.

[Shaptic]

After the refactor based on @sreuland's comment, this would now be:

txnBuilder.setSorobanData(
  new SorobanDataBuilder(sorobanTxData)
    .setReadOnly(footprint.readOnly())
    .setReadWrite(footprint.readWrite())
    // or, equivalently: setFootprint(footprint.readOnly(), footprint.readWrite())
    .build()
);