Multi-source data import and export extension for APISIX Dashboard

​ A simple route import and export module has been implemented in the current APISIX dashboard. But its implementation faces several problems. ​ First of all, in the currently implemented route data handler, the code is very complicated and does not follow the OAS 3.0. It also makes extensive use of custom variables and other non-standard formats. ​ Also the APISIX Dashboard V3 refactoring plan already had a detailed roadmap with some changes that will affect the operation of the current data export and import module. ​ This proposal aims to implement a general data loader and exporter for APISIX, so that it can be extended to support a wider range of data formats while adhering to open standards and also improves compatibility and extensibility.