* Use <number>.<number> format for Google Analytics client ID
With the `ENFORCE_RECOMMENDATIONS` [validation behavior](https://developers.google.com/analytics/devguides/collection/protocol/ga4/validating-events?client_type=firebase#send_events_for_validation), Google Analytics warns about client IDs not in the <number>.<number> format.
This is not an issue in practice - that recommendation is for compatibility with existing client IDs and events are still processed with a client ID in any format. Additionally, the validation is not enabled by default.
However, this PR updates our sample code to use a consistent ID regardless to reduce noise if the validation is enabled. We use a random ID concatenated with a UNIX timestamp to match other GA client libraries.
* Run eslint
Updates a nunber of dependencies in a single PR. These were
suggested by dependabot but updating them individually would
mean the reposistory would be in a broken state until everything
had merged.
I'm not personally a huge fan of lowercasing doctype, but
Prettier has taken an opinionated stance here and there is not a
way to disable it:
https://github.com/prettier/prettier/issues/15096
