feat: join call route

Signed-off-by: Infi <infi@infi.sh>

app/src/main/java/chat/revolt/api/routes/voice/Voice.kt

@@ -0,0 +1,35 @@
+package chat.revolt.api.routes.voice
+
+import chat.revolt.api.RevoltError
+import chat.revolt.api.RevoltHttp
+import chat.revolt.api.RevoltJson
+import chat.revolt.api.api
+import io.ktor.client.request.post
+import io.ktor.client.request.setBody
+import io.ktor.client.statement.bodyAsText
+import io.ktor.http.ContentType
+import io.ktor.http.contentType
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.SerializationException
+
+@Serializable
+data class JoinCallResponse(
+    val token: String,
+    val url: String,
+)
+
+suspend fun joinCall(channelId: String, nodeName: String): JoinCallResponse {
+    val response = RevoltHttp.post("/channels/$channelId/join_call".api()) {
+        contentType(ContentType.Application.Json)
+        setBody(mapOf("node" to nodeName))
+    }.bodyAsText()
+
+    try {
+        val error = RevoltJson.decodeFromString(RevoltError.serializer(), response)
+        throw Exception(error.type)
+    } catch (e: SerializationException) {
+        // Not an error
+    }
+
+    return RevoltJson.decodeFromString(JoinCallResponse.serializer(), response)
+}