Add compute unit helpers

[lorisleiva]

This PR brings the following high-level helpers to the @solana-program/compute-budget JS client:

• const MAX_COMPUTE_UNIT_LIMIT (1_400_000): The maximum units assignable to a transaction. This can be used as a temporary value when simulating a transaction to estimate its actual CU.

• const PROVISORY_COMPUTE_UNIT_LIMIT (0): A temporary value that can be used to signal that the transaction should be simulated to get its CUs before being sent. It is safer to use than MAX_COMPUTE_UNIT_LIMIT because the transaction will fail to execute unless it is properly estimated.

• function estimateComputeUnitLimitFactory: Brought from @solana/kit and renamed it from getComputeUnitEstimateForTransactionMessageFactory since the function is now part of a narrower namespace (i.e. @solana-program/compute-budget). Aside from being renamed and refactored internally to use some more granular helpers, it works exactly the same. Tests were also brought from @solana/kit and converted from Jest to Vitest.

  const estimateCUs = estimateComputeUnitLimitFactory({ rpc });
  
  const estimatedCUs: number = await estimateCUs(transactionMessage);

• function estimateAndUpdateProvisoryComputeUnitLimitFactory: A slightly higher-level helper that accepts a function returned by estimateComputeUnitLimitFactory and return a function that estimates and updates the compute unit limit instruction if and only if it isn't already set to an explicit value (i.e. not PROVISORY_COMPUTE_UNIT_LIMIT nor MAX_COMPUTE_UNIT_LIMIT).

  const estimateAndUpdateCUs = estimateAndUpdateProvisoryComputeUnitLimitFactory(
      estimateComputeUnitLimitFactory({ rpc })
  );
  
  const transactionMessageWithCUs = await estimateAndUpdateCUs(transactionMessage);

• function updateOrAppendSetComputeUnitLimitInstruction: Updates the first SetComputeUnitLimit instruction in a transaction message with the given units, or appends a new instruction if none exists. A function of the current value can be provided instead of a static value.

  const updatedTransactionMessage = updateOrAppendSetComputeUnitLimitInstruction(
    // E.g. Keep the current limit if it is set, otherwise set it to the maximum.
    (currentUnits) => currentUnits === null ? MAX_COMPUTE_UNIT_LIMIT : currentUnits,
    transactionMessage,
  );

• function fillProvisorySetComputeUnitLimitInstruction : Appends a SetComputeUnitLimit instruction with a provisory compute unit limit to a given transaction message if and only if it does not already have one.

  const transactionMessage = pipe(
    createTransactionMessage({ version: 0 }),
    fillProvisorySetComputeUnitLimitInstruction,
    // ...
  );

• function updateOrAppendSetComputeUnitPriceInstruction : Updates the first SetComputeUnitPrice instruction in a transaction message with the given micro-Lamports, or appends a new instruction if none exists. A function of the current value can be provided instead of a static value.

  const updatedTransactionMessage = updateOrAppendSetComputeUnitPriceInstruction(
    // E.g. double the current price or set it to 10_000 if it isn't set.
    (currentPrice) => currentPrice === null ? 10_000 : currentPrice * 2,
    transactionMessage,
  );

• function setTransactionMessageComputeUnitPrice : Appends a SetComputeUnitPrice instruction with the provided micro-Lamports.

  const transactionMessage = pipe(
    createTransactionMessage({ version: 0 }),
    (m) => setTransactionMessageComputeUnitPrice(10_000, m),
    // ...
  );

Note that some of these helpers will be useful when configuring TransactionPlanners and TransactionPlanExecutors in the future. At this point, we may consider adding decorators for these types directly in this package.