broke out initcluster

One benefit of this is that a typo in annex-cluster-node config won't
init a new cluster.

Also it gets the cluster description set and is consistent with
initremote.

Command/InitCluster.hs

@@ -0,0 +1,50 @@
+{- git-annex command
+ -
+ - Copyright 2024 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU AGPL version 3 or higher.
+ -}
+
+{-# LANGUAGE OverloadedStrings #-}
+
+module Command.InitCluster where
+
+import Command
+import qualified Annex
+import Types.Cluster
+import Logs.UUID
+import Config
+import Annex.UUID
+import Git.Types
+import Git.Remote (isLegalName)
+
+import qualified Data.Map as M
+
+cmd :: Command
+cmd = command "initcluster" SectionSetup "initialize a new cluster"
+	(paramPair paramName paramDesc) (withParams seek)
+
+seek :: CmdParams -> CommandSeek
+seek (clustername:desc:[]) = commandAction $
+	start clustername (toUUIDDesc desc)
+seek (clustername:[]) = commandAction $
+	start clustername $ toUUIDDesc ("cluster " ++ clustername)
+seek _ = giveup "Expected two parameters, name and description."
+
+start :: RemoteName -> UUIDDesc -> CommandStart
+start clustername desc = starting "initcluster" ai si $ do
+	unless (isLegalName clustername) $
+		giveup "That cluster name is not a valid git remote name."
+
+	myclusters <- annexClusters <$> Annex.getGitConfig
+	unless (M.member clustername myclusters) $ do
+		cu <- fromMaybe (giveup "unable to generate a cluster UUID") 
+			<$> genClusterUUID <$> liftIO genUUID
+		setConfig (annexConfig ("cluster." <> encodeBS clustername))
+			(fromUUID (fromClusterUUID cu))
+		describeUUID (fromClusterUUID cu) desc
+
+	next $ return True
+  where
+	ai = ActionItemOther (Just (UnquotedString clustername))
+	si = SeekInput [clustername]