Add Soroswap benchmark mode for apply load.

[dmkozh]

Description

This mode uses the official Soroswap contracts from mainnet. It executes swaps of different token pairs (to allow for parallelism).

This is based on #5201

Checklist

• Reviewed the contributing document
• Rebased on top of master (no merge commits)
• Ran clang-format v8.0.0 (via make format or the Visual Studio extension)
• Compiles
• Ran all tests
• If change impacts performance, include supporting evidence per the performance document

[Copilot]

Pull request overview

Adds new apply-load benchmark “model transaction” options to better simulate real-world Soroban workloads (custom token transfers and Soroswap swaps), including contract/Wasm setup paths and acceptance tests.

Changes:

• Extend ApplyLoadModelTx to support CUSTOM_TOKEN and SOROSWAP, with corresponding setup + transaction generation in ApplyLoad.
• Add token + Soroswap contract Wasms and Rust bridge accessors to embed them into Core for apply-load setup.
• Add acceptance tests and example configs for the new benchmark modes.

Reviewed changes

Copilot reviewed 23 out of 28 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
src/simulation/TxGenerator.h	Adds instruction constants and a new Soroban token-transfer generator API.
src/simulation/TxGenerator.cpp	Implements invokeTokenTransfer for custom token transfers.
src/simulation/ApplyLoad.h	Adds setup/generation helpers and Soroswap benchmark state.
src/simulation/ApplyLoad.cpp	Implements custom token + Soroswap setup and tx generation; refactors benchmarking path.
src/main/Config.h	Extends ApplyLoadModelTx enum.
src/main/Config.cpp	Parses new APPLY_LOAD_MODEL_TX values and updates error message.
src/simulation/test/LoadGeneratorTests.cpp	Adds acceptance tests for benchmark SAC/custom-token/Soroswap and classic TX mix.
src/rust/src/soroban_test_wasm.rs	Exposes embedded apply-load Wasms via Rust helpers.
src/rust/src/bridge.rs	Adds Rust bridge function declarations for the new Wasm getters.
src/rust/apply-load-wasm/*	Adds embedded Wasm blobs (token + Soroswap factory/pool/router) and a README.
scripts/apply_load/token/**	Adds the source workspace and tests for building the custom token Wasm.
docs/apply-load-benchmark-token.cfg	Adds example config for benchmarking custom token transfers.
docs/apply-load-benchmark-sac.cfg	Updates SAC benchmark config header wording.
Builds/VisualStudio/build_rust.bat	Adjusts Rust build flow to rely on cargo’s incremental tracking.
Builds/VisualStudio/stellar-core.vcxproj*	Adds SecretManager sources to the VS project files.

The merge-base changed after approval.