run from app folder, set ld lib path only for emby binary

[aptalca]

Fixes 2 issues:

• Upstream's newly included libc library is screwy and doesn't work with any other OS programs including nc, which breaks the service healthcheck. This PR sets the ld lib path only for the emby binary and not nc
• The binary now requires the working directory to be the app folder, otherwise it complains with a non-descript unable to exec - not found error.

[thespad]

Do we also want to add that libexpat1 dep to the image?

[aptalca]

thanks for the reminder. I'll add it

[LinuxServer-CI]

I am a bot, here are the test results for this PR:
https://ci-tests.linuxserver.io/lspipepr/emby/beta-4.10.0.3-pkg-cc67c1a3-dev-538fc01aa257be99de9992de0a5991aa4ea60f58-pr-115/index.html
https://ci-tests.linuxserver.io/lspipepr/emby/beta-4.10.0.3-pkg-cc67c1a3-dev-538fc01aa257be99de9992de0a5991aa4ea60f58-pr-115/shellcheck-result.xml

Tag	Passed
amd64-beta-4.10.0.3-pkg-cc67c1a3-dev-538fc01aa257be99de9992de0a5991aa4ea60f58-pr-115	✅
arm64v8-beta-4.10.0.3-pkg-cc67c1a3-dev-538fc01aa257be99de9992de0a5991aa4ea60f58-pr-115	✅

[LinuxServer-CI]

I am a bot, here are the test results for this PR:
https://ci-tests.linuxserver.io/lspipepr/emby/beta-4.10.0.3-pkg-cc67c1a3-dev-9e1b186925619cb755f6dd00fc88880391ef327b-pr-115/index.html
https://ci-tests.linuxserver.io/lspipepr/emby/beta-4.10.0.3-pkg-cc67c1a3-dev-9e1b186925619cb755f6dd00fc88880391ef327b-pr-115/shellcheck-result.xml

Tag	Passed
amd64-beta-4.10.0.3-pkg-cc67c1a3-dev-9e1b186925619cb755f6dd00fc88880391ef327b-pr-115	✅
arm64v8-beta-4.10.0.3-pkg-cc67c1a3-dev-9e1b186925619cb755f6dd00fc88880391ef327b-pr-115	✅