Star projection fails to respect `ProjectionIterationBehavior.UNFILTERED`

[dlurton]

As demonstrated with the following unit test:

import com.amazon.ion.system.IonSystemBuilder
import org.junit.Test
import org.partiql.lang.eval.EvaluationSession
import org.partiql.lang.eval.ExprValueFactory
import org.partiql.lang.eval.ProjectionIterationBehavior
import kotlin.test.assertEquals

class ScratchPad {
    @Test
    fun test() {
        val ion = IonSystemBuilder.standard().build()
        val exprFactory = ExprValueFactory.standard(ion)
        val pipeline = CompilerPipeline.build(exprFactory) {
            compileOptions {
                projectionIteration(ProjectionIterationBehavior.UNFILTERED)
            }
        }

        val q = pipeline.compile("select * from <<{'a': MISSING}>>")
        val r = q.eval(EvaluationSession.standard())
        // assertion below fails
        assertEquals("<<{'a': MISSING}>>", r.toString())
    }
}