core: add definePlugin syntax support

packages/hydrooj/src/plugin-api.ts

@@ -5,6 +5,7 @@ import _ from 'lodash';
 import moment from 'moment-timezone';
 import Schema from 'schemastery';
 import superagent from 'superagent';
+import { Context } from './context';
 import db from './service/db';
 export { ObjectID, ObjectId, FilterQuery } from 'mongodb';
 export * from './utils';
@@ -55,3 +56,9 @@ export { EventMap } from './service/bus';
 export {
     db, Schema, yaml, fs, AdmZip, superagent, _, moment,
 };
+export const definePlugin = <T = never>(args: {
+    using?: keyof Context[];
+    apply: (ctx: Context, config: T) => Promise<void> | void;
+    schema?: Schema<T>;
+    name?: string;
+}) => args;