Specialize Comparable#compareTo for boxed primitives

Support Comparable#compareTo for boxed primitive in redundant
boxing/unboxing analysis, along with CHECKCAST to java.lang.Comparable.

Note that we can do that for Float and Double, too, because
Float#compareTo(Float) and Double#compareTo(Double) are delegated to
Float#compare(float, float) and Double#compare(double, double),
respectively.

Fuse specialized comparison for integers with conditional jumps
if possible (both for Comparable#compareTo and Intrinsics#areEqual).

 #KT-11959 Fixed

compiler/testData/codegen/box/boxingOptimization/boxedPrimitivesAreEqual.kt

@@ -0,0 +1,21 @@
+inline fun eq(a: Any, b: Any) = a == b
+inline fun ne(a: Any, b: Any) = a != b
+
+val ONE = 1
+val ONEL = 1L
+
+fun box(): String {
+    return when {
+        eq(ONE, 2) -> "Fail 1"
+        !eq(ONE, 1) -> "Fail 2"
+        !ne(ONE, 2) -> "Fail 3"
+        ne(ONE, 1) -> "Fail 4"
+
+        eq(ONEL, 42L) -> "Fail 1L"
+        !eq(ONEL, 1L) -> "Fail 2L"
+        !ne(ONEL, 42L) -> "Fail 3L"
+        ne(ONEL, 1L) -> "Fail 4L"
+
+        else -> "OK"
+    }
+}