Revisit axios-cookiejar-support

In the 10.0.0 dependency bump, axios-cookiejar-support was left at `^1.0.1` when the latest is `2.0.4`. Why wasn't this updated in line with the others? Well...

- the syntax for how to implement `axios-cookiejar-support` has changed - this is not a big deal. Usage is https://github.com/3846masa/axios-cookiejar-support#usage
- but it turns out `axios-cookiejar-support` doesn't like our use of custom http/https agents. In fact it refuses to run when they are supplied. `Error [axios-cookiejar-support does not support for use with other http(s).Agent.].`

Others have spotted this and the developer's advise is here https://github.com/3846masa/axios-cookiejar-support/issues/431. In short:

- use [http-cookie-agent](https://www.npmjs.com/package/http-cookie-agent) instead. This is another library by the same developer and is actually a dependency of `axios-cookiejar-support`
- configure our agents to use ^
- scrap `axios-cookiejar-support`

Doing it this way may also eliminate this bug at the same time: https://github.com/apache/couchdb-nano/issues/264.

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This seems like it's worth a try, but didn't want to hold up v10 (any more than it was) while fiddling with it.

Start by reviewing the 10.0.0 dependency bump and the code that configures custom http/https agents. Compare the axios-cookiejar-support usage guidance with the linked developer advice and the reported CouchDB Nano bug; done means choosing and implementing a compatible cookie-agent approach, or documenting why the dependency should be removed.

Written by the indexing model from the issue text.