Support Clojure 1.12 array class tokens

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The new foo/3 was reader-illegal prior to 1.12.

Bring in and customize some tools.reader bits and bobs to support reading this new syntax.

Clojure's symbol allows us to construct technically illegal symbols, we take advantage of this to test and support this new syntax in any version of Clojure via, for example, (symbol "foo" "3").

Closes #279

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@borkdude, when you have some time/interest, I think this PR's approach merits a review.

Recap of options from #279 (with some additions). Support new syntax in rewrite-clj by:

1. Waiting for and relying upon an upcoming clojure.tools.reader release that reads this new syntax
2. [this PR] Bringing in necessary support to rewrite-clj itself
3. Entirely inlining clojure.tools.reader and adapting as necessary (this is the approach you took for clj-kondo). This could have other benefits and would make relaxing parsing rules easier.
4. Switching from clojure.tools.reader to edamame. You were half-joking, but it might be an interesting experiment someday. Because you control edamame, it could be adapted/extended however we see fit.

[borkdude]

I'm certainly open to 4 since I have to support the symbol with numeric anyway too. In edamame I also rely on tools.reader btw but only on tools.reader.edn, like rewrite-clj (which was my inspiration initially).

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I had not looked at edamame source code in a while. I kinda like that it is not shy about using clojure.tools.reader impl namespaces. I will keep that in mind for future changes.

I like the idea of exploring using edamame. It would be a bigger change with a (potentially) bigger impact on rewrite-clj users. I guess we could explore edamame separately from this issue/PR. It probably deserves a decision matrix.

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Unless you see a problem with this PR @borkdude, I think I'll go ahead and merge it.

[borkdude]

LGTM!