Avoid primitive boxing for 'boxed == primitive' if possible

This makes sense for non-floating-point primitive type
(boolean, char, byte, short, int, long):
floating-point types use specialized versions of 'areEqual'.

compiler/testData/codegen/bytecodeText/noBoxingForBoxedEqPrimitive.kt

@@ -0,0 +1,26 @@
+fun testBoolean1(a: Boolean?, b: Boolean) = a == b
+fun testBoolean2(a: Boolean?, b: Boolean) = a != b
+
+fun testChar1(a: Char?, b: Char) = a == b
+fun testChar2(a: Char?, b: Char) = a != b
+
+fun testByte1(a: Byte?, b: Byte) = a == b
+fun testByte2(a: Byte?, b: Byte) = a != b
+
+fun testShort1(a: Short?, b: Short) = a == b
+fun testShort2(a: Short?, b: Short) = a != b
+
+fun testInt1(a: Int?, b: Int) = a == b
+fun testInt2(a: Int?, b: Int) = a != b
+
+fun testLong1(a: Long?, b: Long) = a == b
+fun testLong2(a: Long?, b: Long) = a != b
+
+// 2 booleanValue
+// 2 charValue
+// 2 byteValue
+// 2 shortValue
+// 2 intValue
+// 2 longValue
+// 0 valueOf
+// 0 areEqual