add support for remote mapping as in buildarr-sonarr

[scratchmex]

ref: https://buildarr.github.io/plugins/sonarr/configuration/download-clients/#configuring-remote-path-mappings

[Callum027]

Hi @scratchmex, thanks for reporting this issue.

Indeed, I seem to have forgotten to implement remote path mappings in the Radarr plugin, even though it is implemented in the Sonarr plugin.

This might take a little bit of time as the Sonarr plugin and the Radarr plugin are implemented differently, so it is not a straight copy-paste between them. Once I am ready to start working on it, I will update this issue.