Type information lost on Kotlin DSL accessors to typed Kotlin lambda extensions

[eskatos]

Given a plugin that registers a Kotlin lambda with a TypeOf type token:

val typeToken = typeOf<(String) -> String>()
val lambda = { name: String ->  name.toUpperCase() }
extensions.add(typeToken, "lambdaExtension", lambda)

Expected Behavior

The Kotlin DSL accessor for lambdaExtension should be typed Function1<String, String>.

Current Behavior

The Kotlin DSL accessor for lambdaExtension is typed Function1<Object, String>.

Context

Bug report that triggered the investigation: #10729
PR for the above bug that also introduces a test for this issue #10758