[NI] Discriminate integer literal types as they are less specific

Plus simplify code in `ResultTypeResolver` a bit

compiler/testData/diagnostics/tests/numbers/numberAsUnionAndIntersection.kt

@@ -0,0 +1,22 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun test(numbers: List<Number>) {
+
+    // Short <: R, ILT <: R => CST(Short, ILT) = Short
+    // => we should pick Short in such situation as it more specific
+    shortExpected { getShort() ?: 1 }
+
+    // Short <: R, ILT <: R, R <: Comparable<R> =>
+    // Short <: Comparable<R>, ILT <: Comparable<R> =>
+    // Comparable<Short> <: Comparable<R>, Comparable<ILT> <: Comparable<R> =>
+    // R <: Short, R <: ILT =>
+    // R := Short, R := ILT
+    // => we should pick Short as it more specific
+    shortComparable { getShort() ?: 1 }
+}
+
+fun <R> shortExpected(f: () -> R) {}
+fun <R : Comparable<R>> shortComparable(f: () -> R) {}
+
+fun getShort(): Short? = 1

compiler/testData/diagnostics/tests/numbers/numberAsUnionAndIntersection.txt

@@ -0,0 +1,6 @@
+package
+
+public fun getShort(): kotlin.Short?
+public fun </*0*/ R : kotlin.Comparable<R>> shortComparable(/*0*/ f: () -> R): kotlin.Unit
+public fun </*0*/ R> shortExpected(/*0*/ f: () -> R): kotlin.Unit
+public fun test(/*0*/ numbers: kotlin.collections.List<kotlin.Number>): kotlin.Unit