Improve performance of memoized validator functions.

[leblowl]

Replaces #122 to enable edits by maintainers.

[HerbCaudill]

Thanks @leblowl ! I've removed memoization for the individual validators and memoized the validate function instead. It still uses a hash of the graph as the memoization key, but the performance is equivalent to your original change.

benchmark on #122 :

 ✓ packages/auth/src/test/auth.benchmark.ts (1) 3387ms
   ✓ auth (1) 3386ms
     name                      hz     min     max    mean     p75     p99    p995    p999     rme  samples
   · a new member joining  5.0861  178.43  221.59  196.61  209.11  221.59  221.59  221.59  ±5.26%       10

benchmark on this PR:

 ✓ packages/auth/src/test/auth.benchmark.ts (1) 3429ms
   ✓ auth (1) 3428ms
     name                      hz     min     max    mean     p75     p99    p995    p999     rme  samples
   · a new member joining  5.0062  180.69  216.99  199.75  212.02  216.99  216.99  216.99  ±4.39%       10

Let me know what you think, if this looks good to you I'll go ahead and merge it.