Add database optimise task (#3929)

* Add database optimise task
* Wrap errors
* US internationalisation
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Co-authored-by: WithoutPants <53250216+WithoutPants@users.noreply.github.com>

graphql/documents/mutations/metadata.graphql

@@ -45,3 +45,7 @@ mutation BackupDatabase($input: BackupDatabaseInput!) {
 mutation AnonymiseDatabase($input: AnonymiseDatabaseInput!) {
   anonymiseDatabase(input: $input)
 }
+
+mutation OptimiseDatabase {
+  optimiseDatabase
+}