Add insert assets path initializer

What does this MR do and why?

closes #1408 (closed)

Due to https://jihulab.com/gitlab-cn/gitlab/-/blob/22f71dce6990e17bea6c262919d6ae480ffdabf2/config/application.rb#L349, all assets path should be push before #{config.root}/node_modules, and we don't want to couple logic like adding JH modules to assets with upstream any more like what we did in https://gitlab.com/gitlab-org/gitlab/-/merge_requests/88207. With this MR, we make adding JH path works in /jh folder and decouple with upstream.

Screenshots or screen recordings

How to set up and validate locally

1. create node_modules/@jihu-fe/svgs/dist/illustrations/test/test.svg
2. start gitlab in gdk
3. uses the svg any where in rails

MR acceptance checklist

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