ui: add panel/Tasks and use it for the node tasks

this is a panel that is heavily inspired from widget-toolkits
node/Tasks panel, but is adapted to use the extended api calls of
pbs (e.g. since/until filter)

has 'filter' panel (like pmgs log tracker gui), but it is collapsible

if we extend the api calls of the other projects, we can merge this
again into the widget-toolkit one and use that

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

www/Makefile

@@ -36,6 +36,7 @@ JSSRC=							\
 	dashboard/LongestTasks.js			\
 	dashboard/RunningTasks.js			\
 	dashboard/TaskSummary.js			\
+	panel/Tasks.js					\
 	Utils.js					\
 	AccessControlPanel.js				\
 	ZFSList.js					\