Add Browser navigation timing event

[martinkuba]

Changes

This adds a new event for capturing the navigation timing date in browser/web applications.

Merge requirement checklist

• CONTRIBUTING.md guidelines followed.
• Change log entry added, according to the guidelines in When to add a changelog entry.
  • If your PR does not need a change log, start the PR title with [chore]
• schema-next.yaml updated with changes to existing conventions.