Use MongoDB for database. Add small migrate function from MySQL

.drone.yml

@@ -18,10 +18,13 @@ steps:
   environment:
     ConnectionString:
       from_secret: ConnectionString
+      MySQLConnectionString:
+        from_secret: MySQLConnectionString
   commands:
   - chmod +x ./build.sh
   - ./build.sh
   - sed -i "s/<DatabaseConnectionString>/$ConnectionString/g" output/appsettings.json
+  - sed -i "s/<MySQLConnectionString>/$MySQLConnectionString/g" output/appsettings.json
   - cp api.blog.service output/
   - cp -r ./output/* /output
 - name: restart service