feat: add buildData to track serverless functions api version

[jenae-janzen]

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Adds observability to track adoption of the new functions api.

Summary

Fixes #<replace_with_issue_number>

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[github-actions]

📊 Benchmark results

Comparing with 8e0d28d

• Dependency count: 1,369 (no change)
• Package size: 379 MB ⬇️ 0.00% decrease vs. 8e0d28d

[Skn0tt]

Suggested change

	[curr.name]: { display_name: curr.displayName, generator: curr.generator, routes: curr.routes, buildData: curr.buildData },
	[curr.name]: { display_name: curr.displayName, generator: curr.generator, routes: curr.routes, build_data: curr.buildData },

I believe it needs to be snake-case:

https://github.com/netlify/bitballoon/blob/217df0749107d907b3dee20f9054cca6700d2a3e/app/controllers/api/v1/deploys_controller.rb#L99