Replace ULongNumber with JsonPrimitive(ULong)

An overload of JsonPrimitive taking ULong was added in
kotlinx.serialization 1.5.1:
https://github.com/Kotlin/kotlinx.serialization/releases/tag/v1.5.1

gateway/src/commonTest/kotlin/json/SnowflakeTest.kt

@@ -1,13 +1,10 @@
 package dev.kord.gateway.json
 
 import dev.kord.common.entity.Snowflake
+import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.Serializable
-import kotlinx.serialization.decodeFromString
 import kotlinx.serialization.encodeToString
-import kotlinx.serialization.json.Json
-import kotlinx.serialization.json.buildJsonObject
-import kotlinx.serialization.json.decodeFromJsonElement
-import kotlinx.serialization.json.put
+import kotlinx.serialization.json.*
 import kotlin.js.JsName
 import kotlin.test.Test
 import kotlin.test.assertEquals
@@ -56,14 +53,14 @@ class SnowflakeTest {
     @Test
     @JsName("test4")
     fun `Deserialization of Snowflake as large Number completes successfully`() {
-        // ULong is inline class and therefore cannot extend abstract class Number but put only takes Number
-        val value = Snowflake.validValues.last.toNumber()
+        val value = Snowflake.validValues.last
         val json = buildJsonObject {
-            put("snowflake", value)
+            @OptIn(ExperimentalSerializationApi::class)
+            put("snowflake", JsonPrimitive(value))
         }
 
         val container = Json.decodeFromJsonElement<SnowflakeContainer>(json)
-        assertEquals(value.value, container.snowflake.value)
+        assertEquals(value, container.snowflake.value)
     }
 
     @Test

gateway/src/commonTest/kotlin/json/Util.kt

@@ -8,18 +8,3 @@ suspend fun readFile(prefix: String, name: String) = file("gateway", "json/$pref
 infix fun <T> T.shouldBe(that: T) {
     assertEquals(that, this)
 }
-
-fun ULong.toNumber() = ULongNumber(this)
-
-class ULongNumber(val value: ULong) : Number(), Comparable<ULongNumber> {
-    override fun toByte() = value.toByte()
-    override fun toShort() = value.toShort()
-    override fun toInt() = value.toInt()
-    override fun toLong() = value.toLong()
-    override fun toFloat() = value.toFloat()
-    override fun toDouble() = value.toDouble()
-    override fun compareTo(other: ULongNumber) = this.value.compareTo(other.value)
-    override fun equals(other: Any?) = other is ULongNumber && this.value == other.value
-    override fun hashCode() = value.hashCode()
-    override fun toString() = value.toString()
-}