USESI-46 Add Opal GUI ability to show table index log: Full implementati...

...on and a unit test
It's quite possible it throws, but its not relevant. The only strange thing there is the index.delete() being out of the try block. That try was added by me before as i had the impression nothing would show up in opal.log, but lately i have a different impression in dev.
Anyway, i added a new index.delete() in the finally, to make sure any partial changes to the index are cleaned. If delete() can fail, there is really nothing we can do about it