extend pool database with two new tables to store metadata

one of them will be used to persist a queue of metadata to fetch, while the other
is a less volatile storage where metadata gets dumped once fetched.
There's in principle no need for caching or timestamps here since
metadata can't be updated (hash is stored on-chain as part of the
registration) which simplifies a bit the problem.

lib/core/src/Cardano/Pool/DB/Sqlite/TH.hs

@@ -22,6 +22,10 @@ import Prelude
 
 import Cardano.Wallet.DB.Sqlite.Types
     ( sqlSettings' )
+import Data.ByteString
+    ( ByteString )
+import Data.Text
+    ( Text )
 import Data.Word
     ( Word32, Word64, Word8 )
 import Database.Persist.Class
@@ -89,4 +93,26 @@ PoolRegistration sql=pool_registration
 
     Primary poolRegistrationPoolId
     deriving Show Generic
+
+-- Temporary queue where metadata to fetch are stored.
+PoolMetadataQueue sql=pool_metadata_queue
+    poolMetadataQueuePoolId            W.PoolId           sql=pool_id
+    poolMetadataQueueUrl               Text               sql=metadata_url
+    poolMetadataQueueHash              ByteString         sql=metadata_hash
+
+    Primary poolMetadataQueuePoolId
+    deriving Show Generic
+
+-- Cached metadata after they've been fetched from a remote server.
+PoolMetadata sql=pool_metadata
+    poolMetadataPoolId                 W.PoolId           sql=pool_id
+    poolMetadataName                   Text               sql=name
+    poolMetadataTicker                 W.StakePoolTicker  sql=ticker
+    poolMetadataDescription            Text Maybe         sql=description
+    poolMetadataHomepage               Text               sql=homepage
+    poolMetadataPledge                 Word64             sql=pledge
+    poolMetadataOwner                  ByteString         sql=owner
+
+    Primary poolMetadataPoolId
+    deriving Show Generic
 |]

lib/core/src/Cardano/Wallet/DB/Sqlite/Types.hs

@@ -36,6 +36,7 @@ import Cardano.Wallet.Primitive.Types
     , PoolOwner (..)
     , SlotId (..)
     , SlotNo (..)
+    , StakePoolTicker
     , TxStatus (..)
     , WalletId (..)
     , flatSlot
@@ -454,3 +455,13 @@ instance PersistField PassphraseScheme where
 
 instance PersistFieldSql PassphraseScheme where
     sqlType _ = sqlType (Proxy @String)
+
+----------------------------------------------------------------------------
+-- StakePoolTicker
+
+instance PersistField StakePoolTicker where
+    toPersistValue = toPersistValue . toText
+    fromPersistValue = fromPersistValueFromText
+
+instance PersistFieldSql StakePoolTicker where
+    sqlType _ = sqlType (Proxy @Text)