mbsync: add option to add extra account configuration

(cherry picked from commit 5770dc58b9)

modules/programs/mbsync-accounts.nix

@@ -89,5 +89,19 @@ in
         Remote store extra configuration.
       '';
     };
+
+    extraConfig.account = mkOption {
+      type = extraConfigType;
+      default = {};
+      example = literalExample ''
+        {
+          PipelineDepth = 10;
+          Timeout = 60;
+        };
+      '';
+      description = ''
+        Account section extra configuration.
+      '';
+    };
   };
 }

modules/programs/mbsync.nix

@@ -60,6 +60,7 @@ let
         }
         // genTlsConfig imap.tls
         // optionalAttrs (imap.port != null) { Port = toString imap.port; }
+        // mbsync.extraConfig.account
       )
       + "\n"
       + genSection "IMAPStore ${name}-remote" (