Player: cache addon stream redirect URLs

[Aztup]

Problem

When using third party addons Stremio passes the full addon URL but most of the time it's a redirect.
This means that on every seek or new segment fetch it goes through the original URL, adding latency and straining the addon server. If the addon server goes down mid-playback, it'll buffer even though the final server is perfectly fine.

Summary

• resolves the redirect url on loadfile command
• reduce load on addons server
• make the streaming experience smoother and faster overall

Benchmark (100 requests)

	Without cache	With cache
Avg	366.0 ms	117.7 ms
Min	153.2 ms	17.7 ms
Max	6617.7 ms	317.4 ms
p50	261.8 ms	106.1 ms
p90	360.2 ms	157.0 ms
p99	3357.9 ms	218.6 ms

Verification

• cargo fmt
• git diff --check
• does not break on local file / torrent
• fallback to the original url if it fails
• clear cache on every new loadfile command + has ttl (some URLs could expire)
• was tested over multiple days with no issues found
• PRs touching (player.rs) that could cause conflicts Feat/bump mpv libmpv2 #59