Introduce support for plugin-defined intrinsics in JVM IR backend:

Add intrinsic for kotlinx.serialization.serializer<T>() function.

Plugin intrinsic for old backend is removed because it is too hard
and unjustifiable to unify them.

plugins/kotlinx-serialization/testData/boxIr/intrinsicsBox.kt

@@ -0,0 +1,62 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// TARGET_BACKEND: JVM_IR
+
+// WITH_STDLIB
+
+import kotlinx.serialization.*
+import kotlinx.serialization.json.*
+import kotlinx.serialization.internal.*
+import kotlinx.serialization.descriptors.*
+
+@Serializable
+class Simple(val firstName: String, val lastName: String)
+
+@Serializable
+data class Box<out T>(val boxed: T)
+
+@Serializable
+object SerializableObject {}
+
+inline fun <reified T : Any> getSer(): KSerializer<T> {
+    return serializer<T>()
+}
+
+inline fun <reified T : Any> getBoxSer(): KSerializer<Box<T>> {
+    return serializer<Box<T>>()
+}
+
+inline fun <reified T : Any> listSer(): KSerializer<List<T>> {
+    return serializer<List<T>>()
+}
+
+fun SerialDescriptor.recursiveToString(): String {
+    return (0 until elementsCount).joinToString(", ", "$serialName(", ")") { i ->
+        getElementName(i) + ": " + getElementDescriptor(i).recursiveToString()
+    }
+}
+
+fun assertHasSerializers(kSerializer: KSerializer<*>, list: List<String>) {
+    var str = kSerializer.descriptor.recursiveToString()
+    for (name in list) {
+        if (name !in str) error("Not found $name in $str")
+        str = str.replaceBefore(name, "")
+        str = str.removePrefix(name)
+    }
+}
+
+fun box(): String {
+    assertHasSerializers(serializer<Simple>(), listOf("Simple"))
+    assertHasSerializers(getSer<Simple>(), listOf("Simple"))
+
+    assertHasSerializers(getSer<Box<Simple>>(), listOf("Box", "Simple"))
+    assertHasSerializers(getBoxSer<Simple>(), listOf("Box", "Simple"))
+
+    assertHasSerializers(listSer<Simple>(), listOf("ArrayList", "Simple"))
+    assertHasSerializers(serializer<Box<List<Simple>>>(), listOf("Box", "ArrayList", "Simple"))
+    assertHasSerializers(listSer<Box<List<Simple>>>(), listOf("ArrayList", "Box", "ArrayList", "Simple"))
+
+    assertHasSerializers(serializer<Int>(), listOf("Int"))
+    assertHasSerializers(serializer<SerializableObject>(), listOf("SerializableObject"))
+    assertHasSerializers(listSer<List<Box<Int>>>(), listOf("ArrayList", "ArrayList", "Box", "Int"))
+    return "OK"
+}