Implement Risk Metrics: Value At Risk

[wtindall1]

Description

Implemented Value at risk in PortfolioStatistics
Added ValueAtRisk indicator

Related Issue

Closes #6811

Motivation and Context

Value at risk was not supported

Requires Documentation Change

How Has This Been Tested?

Ran new and existing tests.
Calculation validated against external data file - Python script can be found in #6811 .

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 @wtindall1! 💪 leaving a couple of comments

[Martin-Molinero]

Thank you! 💪