Launch Lean through the dotnet host in the console optimizer

[jhonabreul]

Description

lean optimize fails every backtest in the linux/arm64 quantconnect/lean image, while lean backtest works:

LeanOptimizer.NewResult(...): Got null/empty backtest result for backtest id '<guid>'

Cause: ConsoleLeanOptimizer executes the Launcher apphost, a native x86-64 executable that cannot run in the arm64 image.

The fix:

• lean-binaries-location now defaults to QuantConnect.Lean.Launcher.dll instead of the apphost.
• ConsoleLeanOptimizer.CreateLeanStartInfo runs .dll locations through the dotnet host, which works on any architecture.
• Explicitly configured executables are still run as they are.

Related Issue

Closes #9821

Motivation and Context

Optimizations are unusable on arm64 hosts running the Lean Docker image.

Requires Documentation Change

No.

How Has This Been Tested?

• ConsoleLeanOptimizerTests: .dll locations (any case) run as dotnet "<dll>" <args> from the launcher directory.
• ConsoleLeanOptimizerTests: configured executables (with or without .exe) run directly, even with the .dll next to them.
• Full QuantConnect.Tests.Optimizer namespace: 187 passed, 0 failed.
• Ran the optimizer in the linux/arm64 image: fails to start Lean on master, completes all backtests with the fix.

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!