Move seo to hydrogen package

[cartogram]

The diff here is a bit whack, but this PR mostly just moves the lib/seo code to hydrogen/src/seo and renamed some files.

Most of the small changes are this:

- import {Seo, type SeoHandleFunction} from '~/lib/seo';
+ import {Seo, type SeoHandleFunction} from '@shopify/hydrogen';

Note the generate-seo-tags.ts file is moving to storefront-kit.

[github-actions]

We detected some changes in packages/*/package.json or packages/*/src, and there are no updates in the .changeset.
If the changes are user-facing and should cause a version bump, run npm run changeset add to track your changes and include them in the next release CHANGELOG.
If you are making simple updates to examples or documentation, you do not need to add a changeset.

[jplhomer]

I like this. It makes sense.