Support setting public static fields in classes

[lispyclouds]

Is your feature request related to a problem? Please describe.
I stumbled onto this when trying to override the Executor for clojure.lang.Agent. The minimum code that needs to run:

(import '[clojure.lang Agent]
        '[java.util.concurrent Executors])

(set! (.-soloExecutor Agent) (Executors/newFixedThreadPool 10))

Currently, as setting of the public static fields in a class isn't supported, this results in the following error:

----- Error --------------------------------------------------------------------
Type:     clojure.lang.ExceptionInfo
Message:  Invalid assignment target
Data:     {:type :sci/error, :line 4, :column 1, :file "foo.clj", :phase "analysis"}
Location: foo.clj:4:1
Phase:    analysis

----- Context ------------------------------------------------------------------
1: (import '[clojure.lang Agent]
2:         '[java.util.concurrent Executors])
3:
4: (set! (.-soloExecutor Agent) (Executors/newFixedThreadPool 10))
   ^--- Invalid assignment target

----- Stack trace --------------------------------------------------------------
user - foo.clj:4:1

Describe the solution you'd like
I should be able to set that field and other public static fields in a class.

Describe alternatives you've considered
None

Additional context
This is mainly for the ability to be able to override the Executors to support virtual threads in core constructs like (future ...)