Refactor: loadExistingHoldings in SetJob use like config

[Romazes]

Description

1. Configuration Update: The loadExistingHoldings configuration in the factory brokerage class is now properly utilized. Previously, this configuration was not correctly applied and was being handled through the factory's BrokerageData dictionary. This update ensures that loadExistingHoldings is initialized correctly by using the configuration settings directly.
2. Project Removal: The ToolBox project has been removed from the solution. We now use the generic DataDownload class from Lean, making the ToolBox project redundant.

Related Issue

N/A

Related PRs

• Feature: Generic brokerage downloader wrapper Lean#8235

Motivation and Context

Configuration Update: The current implementation did not utilize the loadExistingHoldings configuration, leading to potential inconsistencies and manual handling through the brokerageData dictionary. By making this change, we align the loadExistingHoldings initialization with the intended configuration settings, improving code maintainability and clarity.
Project Removal: Removing the ToolBox project simplifies the solution structure and reduces maintenance overhead since the generic DataDownload class from Lean fulfills our requirements.

Requires Documentation Change

N/A

How Has This Been Tested?

• Updated the SetJob method to fetch loadExistingHoldings from the configuration.
• Added a specific internal property in modules.json.
• Tested thoroughly through lean-cli and explicit testing of the lean DLL
• Verified that all functionalities previously handled by the ToolBox project are now covered by the generic DataDownload class from Lean.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• Refactor (non-breaking change which improves implementation)
• Performance (non-breaking change which improves performance. Please add associated performance test and results)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Non-functional change (xml comments/documentation/etc)

Checklist:

• My code follows the code style of this project.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My branch follows the naming convention bug-<issue#>-<description> or feature-<issue#>-<description>

[Martin-Molinero]

Thank you 👍