refactor: remove ChalkConfig

[ee7]

• Followed the steps in the contributor's guide: https://crashoverride.com/docs/other/contributing#filing-the-pull-request
• PR title uses semantic commit messages
• Filled out the template to a useful degree
• Updated CHANGELOG.md if necessary

Issue

#214

Description

Continue from #235, #236, #237, and #329, removing the last usage of the autogenerated types: ChalkConfig.

In particular, this PR removes from the confload module's loadLocalStructs() procedure:

chalkConfig = state.attrs.loadChalkConfig()

but deliberately makes only minimal changes there otherwise for now, so that these PRs are tightly focused. That is, all the addCallback(loadLocalStructs) calls still exist for now, but they do less.

After this PR, it's easy to remove c4autoconf itself.

With this PR:

$ git log -1 --format='%h %s'
de237f0 refactor: remove chalkConfig
$ git grep --ignore-case 'chalkConfig'
src/configs/chalk.c42spec:2647:  gen_typename: "ChalkConfig"