KT-13023 Char operations throw ClassCastException for boxed Chars

Char is not a Number, so we can't use the same coercion strategy for Char members,
since it doesn't work for boxed Chars.

compiler/testData/codegen/box/primitiveTypes/kt13023.kt

@@ -0,0 +1,20 @@
+// WITH_RUNTIME
+
+import kotlin.test.assertEquals
+
+fun box(): String {
+    val b = 'b'
+    val c = 'c'
+    assertEquals('c', b + 1)
+    assertEquals('a', b - 1)
+    assertEquals(1, c - b)
+
+    val list = listOf('b', 'a')
+    assertEquals('c', list[0] + 1)
+    assertEquals('a', list[0] - 1)
+    assertEquals(1, list[0] - list[1])
+    assertEquals(1, list[0] - 'a')
+    assertEquals(1, 'b' - list[1])
+
+    return "OK"
+}