fix(umd): batch requests when using plugins via UMD

[Haroenv]

closes FX-1139
fixes #902

If you're using an UMD, execute of the algolia requester will not be the same in a plugin as in core, as they each have their own algolia requester. To prevent this, and other requesters accidentally being joined, I introduced a requesterId.

I was alternatively thinking of Symbol.for('aa.algolia-requester'), but IE11 doesn't support symbols, and it can't be polyfilled

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[Haroenv]

In https://app.circleci.com/pipelines/github/algolia/autocomplete/2568/workflows/d4dac733-6ac3-4c56-8ae7-e3a062febf97/jobs/13837 you can see the new test fails with the code on next

[tkrugg]

nice test!

Not necessary now but I'd love to see one more test which I think would have prevented this issue: An E2E test using our UMD builds and counting requests.

Overall, having a test suite counting queries as we make changes would make a lot a sense, given the immediate impact on pricing.

[sarahdayan]

Agree on the end-to-end test. I believe this was initially in the PR then removed?

I recall our end-to-end setup not to be optimal, but this is a good opportunity to fix it given that one underlying issue is how we expect all our builds to work similarly (and in this case, they don't).

[Haroenv]

there was an UMD E2E test initially indeed, but it wasn't actually easily testing for the case we were fixing. I'll recreate it in a separate PR

[sarahdayan]

For the record, FX-1228 in the backlog is about this.

[sarahdayan]

LGTM as long as the final points can be checked 👍

Thanks @Haroenv for handling this one so promptly!