Allow multiple schemas to be exposed in one instance (#1450)

The schema to use can be selected through the headers `Accept-Profile` for GET/HEAD and `Content-Profile` for POST/PATCH/PUT/DELETE.

This is based on the https://www.w3.org/TR/dx-prof-conneg/ttps://www.w3.org/TR/dx-prof-conneg/ spec.

Also increase all memory tests by 1M(otherwise CI fails).

Co-authored-by: Mahmoud Kassem <MKassem@gk-software.com>
Co-authored-by: Mahmoud Kassem <mahmoud_k@mail.com>

src/PostgREST/Config.hs

@@ -37,6 +37,7 @@ import Control.Lens                (preview)
 import Control.Monad               (fail)
 import Crypto.JWT                  (StringOrURI, stringOrUri)
 import Data.List                   (lookup)
+import Data.List.NonEmpty          (NonEmpty, fromList)
 import Data.Scientific             (floatingOrInteger)
 import Data.Text                   (dropEnd, dropWhileEnd,
                                     intercalate, lines, splitOn,
@@ -71,7 +72,7 @@ data AppConfig = AppConfig {
     configDatabase          :: Text
   , configAnonRole          :: Text
   , configOpenAPIProxyUri   :: Maybe Text
-  , configSchema            :: Text
+  , configSchemas           :: NonEmpty Text
   , configHost              :: Text
   , configPort              :: Int
   , configSocket            :: Maybe Text
@@ -154,8 +155,8 @@ readOptions = do
       AppConfig
         <$> reqString "db-uri"
         <*> reqString "db-anon-role"
-        <*> optString "openapi-server-proxy-uri"
-        <*> reqString "db-schema"
+        <*> optString "server-proxy-uri"
+        <*> (fromList . splitOnCommas <$> reqValue "db-schema")
         <*> (fromMaybe "!4" <$> optString "server-host")
         <*> (fromMaybe 3000 <$> optInt "server-port")
         <*> optString "server-unix-socket"
@@ -199,6 +200,9 @@ readOptions = do
     reqString :: C.Key -> C.Parser C.Config Text
     reqString k = C.required k C.string
 
+    reqValue :: C.Key -> C.Parser C.Config C.Value
+    reqValue k = C.required k C.value
+
     optString :: C.Key -> C.Parser C.Config (Maybe Text)
     optString k = mfilter (/= "") <$> C.optional k C.string