Add support for only monitoring sessions for specific users

[aksiksi]

The idea is users can pass in a comma-separated list of user IDs (static/auto-generated) and user names. We then check against the list before processing a NowPlaying item. If both the user ID and user name do not match any in the list, we skip processing the entry.

Tested:

[nix-shell:~/repos/prefetcharr]$ cargo test
   Compiling prefetcharr v0.7.4 (/home/aksiksi/repos/prefetcharr)
    Finished test [unoptimized + debuginfo] target(s) in 5.35s
     Running unittests src/main.rs (target/debug/deps/prefetcharr-fa9a8069da698fc5)

running 28 tests
test media_server::embyfin::test::bad_url ... ok
test once::test::different_season ... ok
test once::test::different_series ... ok
test once::test::prune_old ... ok
test media_server::embyfin::test::single_session ... ok
test once::test::twice ... ok
test media_server::plex::test::single_session ... ok
test media_server::plex::test::skip_invalid_sessions ... ok
test media_server::plex::test::name_fallback ... ok
test media_server::embyfin::test::skip_invalid_sessions ... ok
test media_server::embyfin::test::jellyfin_auth ... ok
test media_server::embyfin::test::name_fallback_emby ... ok
test sonarr::test::auth ... ok
test media_server::embyfin::test::emby_auth ... ok
test sonarr::test::put_series ... ok
test sonarr::test::series_emtpy ... ok
test sonarr::test::search_season ... ok
test sonarr::test::series_multiple ... ok
test sonarr::test::series_parse_missing_statistics ... ok
test sonarr::test::series_skip_malformed_series ... ok
test sonarr::test::series_v3 ... ok
test once::test::touch ... ok
test media_server::embyfin::test::interval ... ok
test process::test::monitor ... ok
test process::test::pilot ... ok
test process::test::search_next_filter_users ... ok
test process::test::search_next ... ok
test process::test::search_next_skips_unwanted_users ... ok

test result: ok. 28 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.53s

[p-hueber]

Thanks for the contribution! I won't be able to check it for a few days, but I'll get back to you.

[p-hueber]

@aksiksi looks good to me, thanks!