Remove several unused packages

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Overview

These commits deselect a bunch of unused packages in an attempt to free up some filesystem space. (See https://github.com/Opentrons/opentrons/issues/8184.)

Unfortunately, I still don't think this is enough for a top-level make push to succeed, so https://github.com/Opentrons/opentrons/issues/8184 will stay open.

Changelog

• Removed Python packages for JSON-RPC.
  • Per @sfoster:

    it was a first attempt at making a nice network-transparent interface to the hardware controller for test engineering and others who want to directly interact with it

    i think we're moving away from the concept, you can remove it

  • Also removed chardet, a dependency of this.
• Removed pyserial-asyncio. I couldn't find any instance of import serial_asyncio in Opentrons/opentrons.
• Removed json-c, a library that isn't mandated by anything else that we have installed.
• Removed a bunch of nginx modules that appeared unused to me, judging by our nginx.conf.
• Removed sl. 😢

Review requests

Do any of the removed packages strike you as something that we should definitely not remove?

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Ideas for further work:

• This PR added git, curl, and wget.

  Do we really need git? Do we really need both curl and wget, or can we just pick one?

• Busybox has its own implementations of curl and/or wget (can't remember which, exactly). So we have two implementations installed. Can we get rid of one? Are we accidentally doing this with any other commands?
• Should we strip test files from Python packages, sort of automating the workaround in Opentrons/opentrons#8184?

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Aggregating those further ideas in #144.