Improve type safety for SEO data utilities

[davidhousedev]

WHY are these changes introduced?

This PR brings more consistency to the typing of the seo data utilities. This preserves internal consistency within the module and will hopefully help folks in userland who bring the seo data utility module into their own repos.

WHAT is this pull request doing?

Previously, the collection and product seo data utilities in the demo store inferred the types of the data they returned. In contrast, other seo data utililties annotated the return type with the SeoConfig generic.

I realized that the product and collection utilities were using extracted functions for creating the jsonLd values, but those functions returned the incorrect type. I removed the unnecessary array typing and was then able to add the return typing to collection and product.

Continuation of #757

Checklist

• I've read the Contributing Guidelines
• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've added a changeset if this PR contains user-facing or noteworthy changes
• I've added tests to cover my changes
• I've added or updated the documentation

[davidhousedev]

cc: @frehner @juanpprieto @benjaminsehl this is a re-open of #757

[frehner]

Thanks! Looks like the CI checks are running now, so that's good. Once they pass I'll merge in

[frehner]

Oxygen preview failed. ☹️ Oh well.