fix: kotlin schema extractor fixes

[worstell]

fixes #938
fixes #934
fixes #929

This change fixes the java class resolution issue in module POMs, but I still unfortunately haven't figured out how to do the same for unit tests run from kotlin-runtime/ftl-runtime. So, the change was validated locally instead of in unit tests.

with the given Echo.kt:

package ftl.echo

import ftl.builtin.Empty
import xyz.block.ftl.Context
import xyz.block.ftl.Verb
import java.time.OffsetDateTime
import java.util.ArrayList
import java.util.HashMap

class InvalidInput(val field: String) : Exception()

data class EchoRequest(val name: String?)
data class EchoResponse(
  val message: String,
  val time: OffsetDateTime? = null,
  val arrayList: ArrayList<Empty> = ArrayList(),
  val hashMap: HashMap<String, String> = HashMap()
)
 
@Throws(InvalidInput::class)
@Verb
fun echo(context: Context, req: EchoRequest): EchoResponse {
  return EchoResponse(message = "Hello, ${req.name ?: "anonymous"}!")
}

[alecthomas]

Super bizarre, you'd think it would be able to figure this out itself...

[worstell]

i know 😢 thankfully i came across this issue, which pointed me to this solution