Fix: SymbolMapper Future Security Type

[Romazes]

Description

From support reply:
NYMEX and COMEX adopted the Q, whereas CBOT and CME use a @, to represent the electronic contracts

Add support for new Future exchanges:

Related Issue

closes #15

Motivation and Context

Requires Documentation Change

N/A

How Has This Been Tested?

lean-cli download

lean data download --data-provider-historical IQFeed --data-type Trade --resolution Daily --security-type Future --ticker NQ --market cme --start 20250303 --end 20250404

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>