feat: data representations allow custom parsing and formatting of API fields.

See PR #2523. Most notable code changes:

- Load data representation casts into schema cache.
- Data representations for reads, filters, inserts, updates, views, over joins.
- `CoercibleField` represents name references in queries where coercion may be needed.
- `ResolverContext` help facilitate field resolution during planning.
- Planner 'resolves' names in the API query and pairs them with any implicit conversions to be used in the query builder stage.
- Tests for all of the above.
- More consistent naming (TypedX -> CoercibleX).

New: unit tests for more data representation use cases; helpful as examples as well.

New: update CHANGELOG with data representations feature description.

Fixed failing idempotence test.

New: replace date formatter test with one that does something.

Fixup: inadvertent CHANGELOG change after rebase.

Cleanup: `tfName` -> `cfName` and related.

Document what IRType means.

Formatting.

New: use a subquery to interpret `IN` literals requiring data rep transformation.

- With the previous method, very long queries such as `ANY (ARRAY[test.color('000100'), test.color('CAFE12'), test.color('01E240'), ...` could be generated. Consider the case where the parser function name is 45 characters and there's a hundred literals. That's 4.5kB of SQL just for the function name alone!
- New version uses `unnest`: `ANY (SELECT test.color(unnest('{000100,CAFE12,01E240,...}'::text[]))` to produce a much shorter query.
- This is likely to be more performant and either way much more readable and debuggable in the logs.

src/PostgREST/Plan/MutatePlan.hs

@@ -6,8 +6,9 @@ where
 import qualified Data.ByteString.Lazy as LBS
 
 import PostgREST.ApiRequest.Preferences  (PreferResolution)
-import PostgREST.ApiRequest.Types        (LogicTree, OrderTerm)
-import PostgREST.Plan.Types              (TypedField)
+import PostgREST.ApiRequest.Types        (OrderTerm)
+import PostgREST.Plan.Types              (CoercibleField,
+                                          CoercibleLogicTree)
 import PostgREST.RangeQuery              (NonnegRange)
 import PostgREST.SchemaCache.Identifiers (FieldName,
                                           QualifiedIdentifier)
@@ -18,19 +19,19 @@ import Protolude
 data MutatePlan
   = Insert
       { in_        :: QualifiedIdentifier
-      , insCols    :: [TypedField]
+      , insCols    :: [CoercibleField]
       , insBody    :: Maybe LBS.ByteString
       , onConflict :: Maybe (PreferResolution, [FieldName])
-      , where_     :: [LogicTree]
+      , where_     :: [CoercibleLogicTree]
       , returning  :: [FieldName]
       , insPkCols  :: [FieldName]
       , applyDefs  :: Bool
       }
   | Update
       { in_       :: QualifiedIdentifier
-      , updCols   :: [TypedField]
+      , updCols   :: [CoercibleField]
       , updBody   :: Maybe LBS.ByteString
-      , where_    :: [LogicTree]
+      , where_    :: [CoercibleLogicTree]
       , mutRange  :: NonnegRange
       , mutOrder  :: [OrderTerm]
       , returning :: [FieldName]
@@ -38,7 +39,7 @@ data MutatePlan
       }
   | Delete
       { in_       :: QualifiedIdentifier
-      , where_    :: [LogicTree]
+      , where_    :: [CoercibleLogicTree]
       , mutRange  :: NonnegRange
       , mutOrder  :: [OrderTerm]
       , returning :: [FieldName]