add: editWelcomeScreen function

src/helpers/guilds/edit_welcome_screen.ts

@@ -0,0 +1,21 @@
+import { rest } from "../../rest/rest.ts";
+import { ModifyGuildWelcomeScreen } from "../../types/guilds/modify_guild_welcome_screen.ts";
+import { WelcomeScreen } from "../../types/mod.ts";
+import { endpoints } from "../../util/constants.ts";
+import {
+  camelKeysToSnakeCase,
+  snakeKeysToCamelCase,
+} from "../../util/utils.ts";
+
+export async function editWelcomeScreen(
+  guildId: string,
+  options: ModifyGuildWelcomeScreen,
+) {
+  const result = await rest.runMethod(
+    "patch",
+    endpoints.GUILD_WELCOME_SCREEN(guildId),
+    camelKeysToSnakeCase(options),
+  );
+
+  return snakeKeysToCamelCase<WelcomeScreen>(result);
+}