feat: JWT cache implementation based on sieve algorithm (#4084)

Changes:

1. Refactoring and some cleanup of JWT handling code:
* Instead of caching AuthResult cache decoded claims (which signature was verified). Validating claims and determining role is done after cache lookup
* Cleaned up API so that usage of it is simplified: lookupJwtCache cache key >>= parseClaims configJwtAud time
* Handling of JwtCacheState initialization and updates of configuration is encapsulated in Auth.JwtCache module

2. Generic high performance (hopefully) scalable, dynamically resizeable cache implementation based on stm, stm-hamt and sieve algorithm. It also integrates with PostgREST measurements infrastructure providing usage stats (ie. hit ratio, evictions count)

src/PostgREST/Logger.hs

@@ -100,6 +100,12 @@ observationLogger loggerState logLevel obs = case obs of
   o@PoolRequestFullfilled ->
     when (logLevel >= LogDebug) $ do
       logWithZTime loggerState $ observationMessage o
+  o@JwtCacheEviction ->
+    when (logLevel >= LogDebug) $ do
+      logWithZTime loggerState $ observationMessage o
+  o@(JwtCacheLookup _) ->
+    when (logLevel >= LogDebug) $ do
+      logWithZTime loggerState $ observationMessage o
   o ->
     logWithZTime loggerState $ observationMessage o