Task: Sub directory support #1

Description

Support instances where the server is not hosted at the root of the URL, this is handled initially during the version check but the extra path is not persisted in the lookup data for the other requests so they will not work correctly

This is behavior implement in the standalone client through PocketRelay/Client#22 and needs to be ported to this version aswell

Checklist

• URL base path is persisted in the lookup data and used for further requests
• Server can be hosted outside the root of the nginx path