Migrate boxInline tests to new multi-file framework

compiler/testData/codegen/boxInline/syntheticAccessors/constField.kt

@@ -0,0 +1,27 @@
+// FILE: 1.kt
+
+package test
+
+private const val packageProp = "O"
+
+internal inline fun packageInline(p: (String) -> String): String {
+    return p(packageProp)
+}
+
+internal fun samePackageCall(): String {
+    return packageInline { it + "K"}
+}
+
+// FILE: 2.kt
+
+import test.*
+
+fun box(): String {
+    val packageResult = packageInline { it + "K" }
+    if (packageResult != "OK") return "package inline fail: $packageResult"
+
+    val samePackageResult = samePackageCall()
+    if (samePackageResult != "OK") return "same package inline fail: $samePackageResult"
+
+    return "OK"
+}