feat(gatsby-plugin-typography): Hot Reloading for Google Fonts

[LekoArts]

So until now only the hot reloading for normal CSS styles worked but not the <link /> tags for Google's CDN. With this PR also the links to Google will update.

PR #9099 can be closed with this.
Closes #7399
Closes #9095

---

Changes explained:

gatsby-browser

• Only require stuff in develop to keep build bundle size down
• Use DOMParser workaround to set data-gatsby-typography to element to later be able to find it again
• Remove old instance of link tag when updating
• Only do this whole stuff if googleFonts is in the config

gatsby-ssr

• Only add it on build because otherwise we'd have duplicate content during development

[KyleAMathews]

Thanks!

[pieh]

Thanks @LekoArts! 🙏