support for Decimal.isInfitite and isNan

lynglib/src/commonTest/kotlin/net/sergeych/lyng/DecimalModuleTest.kt

@@ -51,6 +51,21 @@ class DecimalModuleTest {
         )
     }
 
+    @Test
+    fun testDecimalIsInfiniteAndIsNaN() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            import lyng.decimal
+
+            assertEquals(false, 0.d.isInfinite())
+            assertEquals(false, "12.34".d.isInfinite())
+            assertEquals(false, 0.d.isNaN())
+            assertEquals(false, "12.34".d.isNaN())
+            """.trimIndent()
+        )
+    }
+
     @Test
     fun testDecimalModuleMixedIntOperators() = runTest {
         val scope = Script.newScope()