Add first implementation of the Emacs Lisp representer

[fapdash]

Heavily inspired by the Clojure representer implementation by @bobbicodes.

TODOs

• Adjust src/init.el, see A minor problem in tools/install-packages.el emacs-lisp#469 and Revised tools/install-packages.el (#469) emacs-lisp#470
• Regenerate src/symbols-from-obarray.el
  1. Symbols changed in new Emacs version
  2. String representation of hash tables has been improved in Emacs 30, see this blog post
• Fix all errors from tests/docstrings/docstrings.el
• Probably we're missing some test cases / possible normalizations?
• download solutions for testing of representer efficiency
  • https://github.com/IsaacG/exercism-py/blob/612831462c2e1736fdc3e8ccb96958eac543b467/exercism.py#L65-L76
  • https://exercism.org/api/v2/tracks/emacs-lisp/exercises/two-fer/community_solutions

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I originally worked on this here, but moved the PR to the official repo for better visibility. Maybe someone else is really motivated to push the code over the finish line. I'm still chipping away on this from time to time, eventually I shall finish. :)