Fix Jellyfin for LG webOS

[Noneangel]

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• I have read the contributing guideline and understand that I have made the correct modifications

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closes #627

Description

Before this patch, using the jellyfin-webos client to connect to a Jellyfin server behind a nginx reverse proxy using the jellyfin.subdomain.conf.sample resulted in Error -27 described here.
I removed X-Frame-Options header if the http_user_agent contains Web0S, and it fix the Error -27.

Caution

The name of the os is WebOS (with the letter O), but the user agent is Web0S with the number 0 as documented here.

How Has This Been Tested?

This post suggested testing the presence / absence of SAMEORIGIN using this command:
curl -I -X GET $jellyfin_url to check if X-Frame-Options was set to SAMEORIGIN.
Using the unpatched conf, X-Frame-Options is set to SAMEORIGIN (and error -27 appears)
Using my patched conf, X-Frame-Options is not present, and the jellyfin-webos client can connect to the server.

Caution

I only tested the jellyfin.subdomain.conf, not the jellyfin.subfolder.conf.

Source / References

In the Jellyfin doc for nginx, there is a note:

NOTE: X-Frame-Options may cause issues with the webOS app

[quietsy]

I solved the same issue with:

add_header Access-Control-Allow-Origin "luna://com.webos.service.config" always;

I think it's more secure this way, can you test it out?

[Noneangel]

Your solution is working.

[quietsy]

Looks good, thanks for the PR