Aggregate frames by BCI (java)

[Jongy]

In parallel to #799 which suggests to add "line-in-function" line numbers to Java, on top of the "line-of-function" that we already have - this ticket is about "bci".

If you run --java-line-numbers=bci I expect each frame to have :bci of the AP sample. I have a demo AP changeset that does it: Granulate/async-profiler@4d587e2. Let's add it properly (and change @ to : to match the line numbers).