feat: disable proxy #2

The main use case is for when I'm running a local instance of the OMSS provider within my local network or Raspberry Pi, then there would be no need for the proxy since the IP is still the same.

It would be nice if there was a global environment flag or configuration to disable the proxy behaviour, since it's added overhead that might not be necessary for all situations.

It's also useful because I would like to use the spec to write some providers that can work with Stremio (awesome, that that's already natively supported), but also Nuvio providers, which are basically self-contained singular javascript files that can be executed by the local device (using QuickJS) without needing to host or proxy it on a server (severely reducing the barrier to entry for using providers). An example compiled provider is available here on the main branch.

I already have a working version that compiles the provider into a single script (and unraveling the proxy URL from the source and subtitles), I can contribute it back into a public fork in due course, in case it's something that's useful - but that's not the main focus of this PR.