RFC: execute finally block after break from try..finally in a loop (ref #12806)

[ihnorton]

Replace break and continue statements inside of a try block with a labeled break to the finally handler, followed by a conditional unlabeled break, which will then be the intended loop-exit. Fixes #12806; new tests added from reworked examples there and in #1784.

I'd like some feedback on one consequence. Given the following example:

for i in 1:2
try
    break
catch
finally
    println("fin $1")
    i == 1 && continue
end
end

On master, the loop just exits -- the finally block is not executed (i.e., #12806).
With this patch, it is possible to continue after breaking to the finally block:

fin 1
fin 2

(without the continue, we only hit finally once, as expected)

[JeffBezanson]

Wow, doing continue inside finally is pretty evil. This behavior seems ok to me though.

[JeffBezanson]

Where does x come from? I think the return above is causing these tests to be skipped.

[JeffBezanson]

Fixed by #24075.