Aggregate frames by BCI (java)

In parallel to https://github.com/Granulate/gprofiler/issues/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: https://github.com/Granulate/async-profiler/commit/4d587e213d3fe476d0bc15c8ffc95def6bb33d3a. Let's add it properly (and change `@` to `:` to match the line numbers).