feat: Migrate Combo (S1) to S2 as a pre-alpha component

[tanugarg04]

feat: Migrate Combo to S2 as a pre-alpha component

Description

Adds Combo — an overlay of a Bar mark and a Line mark in the same chart — to
react-spectrum-charts-s2's pre-alpha tier, following the same model as Scatter/Donut
(and mirroring how S1 keeps Combo in its own alpha tier rather than GA).

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

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

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

🎨 Storybook -> https://opensource.adobe.com/react-spectrum-charts/PR-875

🎨 S2 Storybook -> https://opensource.adobe.com/react-spectrum-charts/PR-875-s2

📚 Docs -> https://opensource.adobe.com/react-spectrum-charts/PR-875-docs/