Add IOException constructor(message: Throwable?)

[martinkretzschmar]

IOException lacks the secondary constructor public constructor(message: Throwable?). The standard exceptions in the Kotlin stdlib and java.io.IOException (= the JVM actual) all have this constructor.

Would it be possible to add it?

Background: this would let us mechanically (without special casing this constructor) replace java.io.IOException with kotlinx.io.IOException as we migrate our codebase to KMP.