Bug 1845362 - SSR support for Glean.js

[rosahbruno]

Adds additional checks to verify window and localStorage object exist before making any calls. This handles errors that are ONLY generated when compiling an SSR project. If you run an SSR project locally, the errors don't show because the browser has access to the window object.

This was tested by

• Creating a new nextjs project
• Integrating Glean.js
• Locally running next dev
• Building locally via next build
• Running the out directory on a simple web server via Python from my mac python3 -m http.server

Pull Request checklist

• Quality: Make sure this PR builds and runs cleanly.
  • Inside the glean/ folder, run:
    • npm run test Runs all tests
    • npm run lint Runs all linters
• Tests: This PR includes thorough tests or an explanation of why it does not
• Changelog: This PR includes a changelog entry to CHANGELOG.md or an explanation of why it does not need one
• Documentation: This PR includes documentation changes, an explanation of why it does not need that or a follow-up bug has been filed to do that work
  • Documentation should be added to The Glean Book when making changes to Glean's user facing API
    • When changes to the Glean Book are necessary, link to the corresponding PR on the mozilla/glean repository
  • Documentation should be added to the Glean.js developer documentation when making internal code changes

[chutten]

Normally I'd ask for instrumentation and a test, but it's likely a little difficult to instrument in a situation where instrumentation isn't possible and mocking window to be undefined might be tricky, too.