Expose ToketBucket as a standalone component

[Roman Glushko]

The hyx.ratelimit package provides TokenBucketLimiter component:

hyx/hyx/ratelimit/managers.py

Line 12 in 365a280

 class TokenBucketLimiter(RateLimiter): 

Its API is rather simplistic and hard to reuse if you want to pull that bucket logic to reuse somewhere (for example, to implement a custom bucket retry).

Let's refactor the TokenBucket logic out of the ratelimiter and expose it outside of Hyx, so other projects could import it.