fix: Performance and high memory usage of relation hint calculation

* Calculation of hint message when requested relation is not present in schema cache requires creation of a FuzzySet (to use fuzzy search to find candidate tables). For schemas with many tables it is costly.
This patch introduces dbTablesFuzzyIndex in SchemaCache to memoize the FuzzySet creation.

* Additionally, because of FuzzySet large memory requirements, this patch introduces a limit of 500 relations per schema, above which FuzzySet is not created and hint calculation disabled.

src/PostgREST/Response.hs

@@ -213,10 +213,10 @@ actionResponse (MaybeDbResult InspectPlan{ipHdrsOnly=headersOnly} body) _ versio
   in
   Right $ PgrstResponse HTTP.status200 (MediaType.toContentType MTOpenAPI : cLHeader ++ maybeToList (profileHeader schema negotiatedByProfile)) rsBody
 
-actionResponse (NoDbResult (RelInfoPlan qi@QualifiedIdentifier{..})) _ _ _ SchemaCache{dbTables} _ _ =
+actionResponse (NoDbResult (RelInfoPlan qi@QualifiedIdentifier{..})) _ _ _ sc@SchemaCache{dbTables} _ _ =
   case HM.lookup qi dbTables of
     Just tbl -> respondInfo $ allowH tbl
-    Nothing  -> Left $ Error.SchemaCacheErr $ Error.TableNotFound qiSchema qiName (HM.elems dbTables)
+    Nothing  -> Left $ Error.SchemaCacheErr $ Error.TableNotFound qiSchema qiName sc
   where
     allowH table =
       let hasPK = not . null $ tablePKCols table in