Web console: fix pagination, add error delimiters

[vogievetsky]

This PR fixes the pagination control count and adds delimiters (/) for the error display:

[fjy]

nit:
I would use newline for Failed task id, On host, Debug
and add another delimiter for the sub-items under debug (download, archive, etc)

[vogievetsky]

Ok, I rejiggered it a bit:

There is only one item under Debug, it is "download query detail archive" which I just renamed to "get query detail archive" because it is shorter, also get is less likely to be read as a single item vs download. The query detail archive is a single file that contains all the important query and execution details that can be sent to someone for debugging.