Flags API (#9666)

* feat: new routes for flags API

+ flag get
+ flag creation, migration from socket method
+ flag update, migration from socket method
* fixed bug where you could not unassign someone from a flag

* feat: tests for new flags API

added missing files for schema update

* fix: flag tests to use Write API instead of sockets

* feat: flag notes API + tests

* chore: remove debug line

* test: fix breaking test on mongo

src/middleware/assert.js

@@ -8,6 +8,7 @@
 const path = require('path');
 const nconf = require('nconf');
 
+const db = require('../database');
 const file = require('../file');
 const user = require('../user');
 const groups = require('../groups');
@@ -52,6 +53,14 @@ Assert.post = helpers.try(async (req, res, next) => {
 	next();
 });
 
+Assert.flag = helpers.try(async (req, res, next) => {
+	if (!await db.isSortedSetMember('flags:datetime', req.params.flagId)) {
+		return controllerHelpers.formatApiResponse(404, res, new Error('[[error:no-flag]]'));
+	}
+
+	next();
+});
+
 Assert.path = helpers.try(async (req, res, next) => {
 	// file: URL support
 	if (req.body.path.startsWith('file:///')) {