Fix CCE in generated code that happens when comparing boxed chars

The problem was that when obtaining char from the wrapper,
codegen used int as expected type that led
to a ClassCastException: java.lang.Character cannot be cast to java.lang.Number

The solution is using coercion to chars, it's still correct,
because of implicit widening coercion in JVM from C to I

 #KT-15105 Fixed

compiler/testData/codegen/light-analysis/binaryOp/compareBoxedChars.txt

@@ -0,0 +1,5 @@
+@kotlin.Metadata
+public final class CompareBoxedCharsKt {
+    public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
+    public final static method id(p0: java.lang.Object): java.lang.Object
+}