fix: 修复配置插件页面时报错情况

[scott-leung]

修复 app.wpy 中添加插件页面路径时的报错。

• 在 pages 遍历之前过滤插件页面路径
• 在分包的 pages 遍历之前过滤插件页面路径

Issue #2710 Closes #2710

Checklist

• [x] npm run test passes
• [x] tests and/or benchmarks are included
• [x] cases or donate is changed or added
• [x] documentation is changed or added

[coveralls]

Coverage decreased (-0.005%) to 34.8% when pulling 9dcf654d0827f7a83f419db2ae45f279a2943d71 on scott-leung:master into 58acc9bf74a422e465b8fbb205e4905b23683da3 on Tencent:master.

[scott-leung]

这个 filterPagePath 函数放在那里感觉有点不妥，但是 util/ 里面也没有找到跟他性质同类的文件来安放它的去除，烦请各路大神帮忙 review 一下，看怎么处理比较好呢？