Cache utility improvement

[queensferryme]

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• [x] drop CacheKey.is_primitive, users themselves need to ensure passed-in arguments are hashable (being consistent with stdlib functools.cache) 5f82905
• [x] improve CacheKey.make, kwds needs to be sorted and guarded by a sentinel, all arguments must be typed so that (3, int) is different from (3.0, float) when used as cache key df1cc02
• [ ] improve get_cache, something better than fn.__dict__.get("cache") that works with mypy