Jump Next with Priority Order

Using vim-emulation in a popular IDE I enjoyed having `n` mapped to next issue, with this behavior:
```
function! NextIssue(direction)
for type in ['error', 'warning', 'info']
if ale#loclist_jumping#Jump(direction, 1, type)
break
else
echo type
endif
endfor
endfunction
```

It goes to the next error, if there are no errors, it goes to the next warning, or else to the next info.

The code above is my newbie attempt to implement it in vim with ale, but I hit the wall when I discovered `:echo ale#loclist_jumping#Jump('after', 1)` prints `0` regardless if it was or not successful.

I think this feature might probe useful to jump to the important issue faster without having to navigate all the non-critical ones.

Start with the issue's NextIssue(direction) example and the ale#loclist_jumping#Jump entry point. Trace how ALE reports jump success and prioritizes error, warning, and info locations; done means jumping selects the next available location in that priority order and exposes reliable success behavior.

Written by the indexing model from the issue text.