Move UTxO-type specific functions into top-level Migration module.

These functions manipulate concrete wallet types, so it makes more
sense for them to be located in the top-level `Migration` module, which
deals with concrete wallet types.

Conversely, both `Migration.Planning` and `Migration.Selection` use
abstract types for transaction input identifiers.

In response to review feedback:

#2618 (comment)

lib/core/src/Cardano/Wallet/Primitive/Migration.hs

@@ -29,13 +29,14 @@ import Cardano.Wallet.Primitive.Types.Coin
 import Cardano.Wallet.Primitive.Types.Tx
     ( TxConstraints (..), TxIn, TxOut )
 import Cardano.Wallet.Primitive.Types.UTxO
-    ( UTxO )
+    ( UTxO (..) )
 import Data.Generics.Internal.VL.Lens
     ( view )
 import Data.Generics.Labels
     ()
 
 import qualified Cardano.Wallet.Primitive.Migration.Planning as Planning
+import qualified Data.Map.Strict as Map
 
 -- | Represents a plan for migrating a 'UTxO' set.
 --
@@ -66,9 +67,16 @@ createPlan
     -> MigrationPlan s
 createPlan constraints utxo reward = MigrationPlan
     { selections = view #selections plan
-    , unselected = Planning.uncategorizeUTxO (view #unselected plan)
+    , unselected = uncategorizeUTxO (view #unselected plan)
     , totalFee = view #totalFee plan
     }
   where
-    categorizedUTxO = Planning.categorizeUTxO constraints utxo
-    plan = Planning.createPlan constraints categorizedUTxO reward
+    plan = Planning.createPlan constraints (categorizeUTxO utxo) reward
+
+    categorizeUTxO :: UTxO -> Planning.CategorizedUTxO (TxIn, TxOut)
+    categorizeUTxO (UTxO u) = Planning.categorizeUTxOEntries constraints $
+        (\(i, o) -> ((i, o), view #tokens o)) <$> Map.toList u
+
+    uncategorizeUTxO :: Planning.CategorizedUTxO (TxIn, TxOut) -> UTxO
+    uncategorizeUTxO =
+        UTxO . Map.fromList . fmap fst . Planning.uncategorizeUTxOEntries

lib/core/src/Cardano/Wallet/Primitive/Migration/Planning.hs

@@ -28,10 +28,8 @@ module Cardano.Wallet.Primitive.Migration.Planning
     -- * UTxO entry categorization
     , CategorizedUTxO (..)
     , UTxOEntryCategory (..)
-    , categorizeUTxO
     , categorizeUTxOEntries
     , categorizeUTxOEntry
-    , uncategorizeUTxO
     , uncategorizeUTxOEntries
 
     ) where
@@ -45,9 +43,7 @@ import Cardano.Wallet.Primitive.Types.Coin
 import Cardano.Wallet.Primitive.Types.TokenBundle
     ( TokenBundle (..) )
 import Cardano.Wallet.Primitive.Types.Tx
-    ( TxConstraints (..), TxIn, TxOut )
-import Cardano.Wallet.Primitive.Types.UTxO
-    ( UTxO (..) )
+    ( TxConstraints (..) )
 import Data.Either
     ( isRight )
 import Data.Functor
@@ -63,7 +59,6 @@ import qualified Cardano.Wallet.Primitive.Migration.Selection as Selection
 import qualified Cardano.Wallet.Primitive.Types.TokenBundle as TokenBundle
 import qualified Data.Foldable as F
 import qualified Data.List as L
-import qualified Data.Map.Strict as Map
 
 --------------------------------------------------------------------------------
 -- Migration planning
@@ -213,14 +208,6 @@ data CategorizedUTxO i = CategorizedUTxO
     }
     deriving (Eq, Show)
 
-categorizeUTxO
-    :: TxSize s
-    => TxConstraints s
-    -> UTxO
-    -> CategorizedUTxO (TxIn, TxOut)
-categorizeUTxO constraints (UTxO u) = categorizeUTxOEntries constraints $
-    (\(i, o) -> ((i, o), view #tokens o)) <$> Map.toList u
-
 categorizeUTxOEntries
     :: forall i s. TxSize s
     => TxConstraints s
@@ -260,9 +247,6 @@ categorizeUTxOEntry constraints b
     coinIsIgnorable :: Coin -> Bool
     coinIsIgnorable c = c <= txInputCost constraints
 
-uncategorizeUTxO :: CategorizedUTxO (TxIn, TxOut) -> UTxO
-uncategorizeUTxO = UTxO . Map.fromList . fmap fst . uncategorizeUTxOEntries
-
 uncategorizeUTxOEntries :: CategorizedUTxO i -> [(i, TokenBundle)]
 uncategorizeUTxOEntries utxo = mconcat
     [ supporters utxo