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>

postgrest.cabal

@@ -148,6 +148,7 @@ test-suite spec
                       Feature.UpsertSpec
                       Feature.RawOutputTypesSpec
                       Feature.HtmlRawOutputSpec
+                      Feature.MultipleSchemaSpec
                       SpecHelper
                       TestTypes
   hs-source-dirs:     test