Export clj-kondo config

[Deraen]

https://github.com/clj-kondo/clj-kondo/blob/master/doc/config.md#exporting-and-importing-configuration

Reagent has at least the with-let macro that would benefit from clj-kondo configuration. At the simplest, it can be a lint-as let option, but we could also add a hook that allows the finally form.