lint(track_config): add initial exercises checks

[ee7]

This is still a WIP - just showing one of the things that's in the pipeline.

Before merging this PR I need to:

• Allow not printing an error message for a required array key that is empty (done by lint(validators): support empty array as value of required key #262)

For a future PR:

• Improve the error messages, and especially the context
• Implement checks for e.g. kebab-case, uniqueness, and matching

As of https://github.com/exercism/configlet/pull/260/commits/3716cf51811efd01107eb88676d6a41299681a85c, this PR currently produces the below diff to the configlet lint output. As I said, the error messages should be improved later.

bash

+Missing key: 'practices':
+./config.json
+

clojure

+Array is empty: 'prerequisites':
+./config.json
+

common-lisp

+Array is empty: 'prerequisites':
+./config.json
+
+Configlet detected at least one problem.
+For more information on resolving the problems, please see the documentation:
+https://github.com/exercism/docs/blob/main/building/configlet/lint.md

cpp

+Missing key: 'name':
+./config.json
+
+The 'prerequisites' array contains a zero-length string:
+./config.json
+

csharp

+Array is empty: 'prerequisites':
+./config.json
+
+Configlet detected at least one problem.
+For more information on resolving the problems, please see the documentation:
+https://github.com/exercism/docs/blob/main/building/configlet/lint.md

dart

+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Array is empty: 'prerequisites':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'prerequisites':
+./config.json
+

elixir

+Array is empty: 'prerequisites':
+./config.json
+
+Configlet detected at least one problem.
+For more information on resolving the problems, please see the documentation:
+https://github.com/exercism/docs/blob/main/building/configlet/lint.md

elm

+Array is empty: 'prerequisites':
+./config.json
+
+Configlet detected at least one problem.
+For more information on resolving the problems, please see the documentation:
+https://github.com/exercism/docs/blob/main/building/configlet/lint.md

fsharp

+Array is empty: 'prerequisites':
+./config.json
+
+Configlet detected at least one problem.
+For more information on resolving the problems, please see the documentation:
+https://github.com/exercism/docs/blob/main/building/configlet/lint.md

go

+Array is empty: 'prerequisites':
+./config.json
+

j

+Missing key: 'difficulty':
+./config.json
+
+Missing key: 'difficulty':
+./config.json
+
+Missing key: 'difficulty':
+./config.json
+
+Missing key: 'difficulty':
+./config.json
+
+Missing key: 'difficulty':
+./config.json
+
+Missing key: 'difficulty':
+./config.json
+
+Missing key: 'difficulty':
+./config.json
+

java

+Array is empty: 'prerequisites':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Configlet detected at least one problem.
+For more information on resolving the problems, please see the documentation:
+https://github.com/exercism/docs/blob/main/building/configlet/lint.md

javascript

+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Array is empty: 'prerequisites':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Configlet detected at least one problem.
+For more information on resolving the problems, please see the documentation:
+https://github.com/exercism/docs/blob/main/building/configlet/lint.md

julia

+Array is empty: 'prerequisites':
+./config.json
+
+Missing key: 'name':
+./config.json
+

kotlin

+Missing key: 'name':
+./config.json
+
+Array is empty: 'prerequisites':
+./config.json
+

purescript

+Missing key: 'name':
+./config.json
+
+Array is empty: 'prerequisites':
+./config.json
+

python

+Array is empty: 'prerequisites':
+./config.json
+
+Configlet detected at least one problem.
+For more information on resolving the problems, please see the documentation:
+https://github.com/exercism/docs/blob/main/building/configlet/lint.md

research_experiment_1

+Not an object: 'exercises':
+./config.json
+

ruby

+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Array is empty: 'concepts':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Array is empty: 'concepts':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Array is empty: 'prerequisites':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+
+Missing key: 'name':
+./config.json
+

rust

+Array is empty: 'prerequisites':
+./config.json
+
+Configlet detected at least one problem.
+For more information on resolving the problems, please see the documentation:
+https://github.com/exercism/docs/blob/main/building/configlet/lint.md

swift

+Array is empty: 'prerequisites':
+./config.json
+

x86-64-assembly

+Missing key: 'name':
+./config.json
+
+Array is empty: 'prerequisites':
+./config.json
+

zig

+Missing key: 'practices':
+./config.json
+
+Configlet detected at least one problem.
+For more information on resolving the problems, please see the documentation:
+https://github.com/exercism/docs/blob/main/building/configlet/lint.md