feat: add support for color transparency using @ notation

[divyanshub024]

Description

Add support for color transparency using @ notation

{
          "type": "container",
          "color": "primary@50",
          "height": 250,
          "width": "maxFinite"
        }

Related Issues

Closes #254

Type of Change

• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to change)
• Code refactor
• Build configuration change
• Documentation
• Chore

[Potatomonsta]

LGTM