feat: Choose random color on collection creation (#3912)

Choose a random color from a shared color palette between backend
and frontend during collection creation.

server/routes/api/collections.test.ts

@@ -1,4 +1,5 @@
 import TestServer from "fetch-test-server";
+import { colorPalette } from "@shared/utils/collections";
 import { Document, CollectionUser, CollectionGroup } from "@server/models";
 import webService from "@server/services/web";
 import {
@@ -1054,6 +1055,7 @@ describe("#collections.create", () => {
     expect(body.data.name).toBe("Test");
     expect(body.data.sort.field).toBe("index");
     expect(body.data.sort.direction).toBe("asc");
+    expect(colorPalette.includes(body.data.color)).toBeTruthy();
     expect(body.policies.length).toBe(1);
     expect(body.policies[0].abilities.read).toBeTruthy();
   });

server/routes/api/collections.ts

@@ -2,6 +2,8 @@ import fractionalIndex from "fractional-index";
 import invariant from "invariant";
 import Router from "koa-router";
 import { Sequelize, Op, WhereOptions } from "sequelize";
+import { randomElement } from "@shared/random";
+import { colorPalette } from "@shared/utils/collections";
 import collectionExporter from "@server/commands/collectionExporter";
 import teamUpdater from "@server/commands/teamUpdater";
 import { sequelize } from "@server/database/sequelize";
@@ -50,7 +52,7 @@ const router = new Router();
 router.post("collections.create", auth(), async (ctx) => {
   const {
     name,
-    color,
+    color = randomElement(colorPalette),
     description,
     permission,
     sharing,