Fix trailing ) from interfering with extraction in Clojure keywords

[eneroth]

Summary

In a form like,

(if condition :bg-white :bg-black)

:bg-black will fail to extract, while :bg-white is extracted as expected. This PR fixes this case, implements more comprehensive candidate filtering, and supersedes a previous PR.

Having recently submitted a PR for handling another special case with Clojure keywords (the presence of : inside of keywords), I thought it best to invert the previous strategy: Instead of handling special cases one by one, consume keywords according to the Clojure reader spec. Consume nothing else, other than strings.

Because of this, this PR is a tad more invasive rather than additive, for which I apologize. The strategy is this:

• Strings begin with a " and ends with an unescaped ". Consume everything between these delimiters (existing case).
• Keywords begin with :, and end with whitespace, or one out of a small set of specific reserved characters. Everything else is a valid character in a keyword. Consume everything between these delimiters, and apply the class splitting previously contained in the outer loop. My previous special case handling of : inside of keywords in Extract candidates with variants in Clojure/ClojureScript keywords #18338 is now redundant (and is removed), as this is a more general solution.
• Discard everything else.

I'm hoping that a strategy that is based on Clojure's definition of strings and keywords will pre-empt any further issues with edge cases.

Closes #18344.

Test plan

• Added failing tests.
• cargo test -> failure
• Added fix
• cargo test -> success

[thecrypticace]

@eneroth Can you see if the checkbox to allow maintainers to edit the PR is checked? I've got a few tweaks I want to make.

[thecrypticace]

Also could use a changelog entry

[eneroth]

Sorry @thecrypticace, from what I can see on Github docs, there's supposed to be a checkbox for me to check here:

But I can't see any. In lieu of that, rebased on main and amended with your changes, and added a change log entry.

[thecrypticace]

Huh that's super weird. I wonder why it's missing. Thanks for making the changes!

[thecrypticace]

Ah weird | b'#' being gone makes the tests fail. I guess we can keep it in for the time being then. 🤔

edit: I know why. It's a bit annoying. We need to read whole keywords then split them into utilities. I wonder if this means we need an expanded character set no matter what.

Can do that as a followup bug fix if we turn out to need that.

[thecrypticace]

I'm gonna go head and merge this so I can get it in. Will fix the failing # test in a followup commit.

[eneroth]

@thecrypticace Ah yeah, because of the syntax <elem>#<id>.<class-1>.<class-2>…<class-n>. This is unfortunately a requirement for Clojure for the Hiccup DSL to work.

[thecrypticace]

Yeah, it makes sense. We just can't be quite as selective about certain characters during the pre-processing stage which is fine.