Feat/batch executor v2

[Agbasimere]

Closes: #27

Description

Implement a helper contract to execute multiple Soroban calls in a single transaction. This contract is designed to be gas-efficient by wrapping multiple invoke_contract calls into a single transaction lifecycle, reducing transaction overhead for complex operations.

Features

• Batch Execution: Takes a list of contract addresses, function symbols, and argument vectors.
• Gas Efficiency: Optimized iteration and direct host invocation using env.invoke_contract.
• Atomicity: Standard Soroban behavior ensures that if any call in the batch fails, the entire transaction reverts.
• Result Retrieval: Returns a Vec<Val> containing the execution results of each sub-call in order.

Implementation Details

• Location: src/batch/lib.rs
• Contract Name: BatchExecutor
• SDK Version: Soroban SDK 22.0.0
• Workspace Integration: Registered as anchorpoint-batch-executor in the root Cargo.toml.

Testing

• Added src/batch/test.rs with unit tests.
• Test suite registers a mock contract and validates that the BatchExecutor correctly handles multiple sequential calls and captures their output values.

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[Ceejaytech25]

@Agbasimere , lgtm!