We can allow user to append their path to "lua_package_path", so that they can load their plugins and other code. For instance, Let the "lua_package_path" to be `"/opt/mycode/?.lua;original_path..."`, then user can put their plugin "my-plugin" as `/opt/mycode/apisix/plugins/my-plugin.lua`, and load it via ``` plugins: - my-plugin ```
This idea comes from Yong Nie's talk "微博基于 APISIX 的定制开发" in 2020 Apache APISIX DevCon. I just move it here for discussion.
