Add support for CFDs

[jhonabreul]

Description

Add support for CFDs:

• Data source
• Historical date
• Trading

Note: this should be merge after https://github.com/QuantConnect/Lean/pull/7861

Related Issue

Closes #10

Motivation and Context

Requires Documentation Change

How Has This Been Tested?

• Unit tests
• Interation with Lean:
  • Important: Forex and Equity CFDs streaming was tested and works, since these subscriptions are re-routed to their underlying data. So multiple combinations were tested: subscribing to the CFD only; subscribing to the underlying (forex or equity) first and then to the CFD; subscribing to the CFD and then to the underlying. This is to make sure the changes to the subscribed tickers dictionary work and data from IB is routed to all subscribed tickers to the same data stream.

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)
• [x] 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:

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