Binary profile processing code cleanup

[akvlad]

What

There is a submodule to work with pprof inside the Pyroscope API module: https://github.com/metrico/qryn/tree/master/pyroscope/pprof-bin . As far as it works with binary data at most, it's written in Rust and compiled as a wasm module.

We have to clean the code of the module.

Why

As far as it was the one of the first pieces of Rust code written by its developer, the quality of code can be much better.

Also there may be unoptimized pieces of code with underline memory copy unnoticed.

How

We have to do a set of steps in order to raise the quality of code.

• extend the Tree struct methods with the main elementary methods of working with Trees https://github.com/metrico/qryn/blob/master/pyroscope/pprof-bin/src/lib.rs#L73 #561
• functionally decompose huge merge, bfs, merge_trie, diff_tree functions so they become easier to read
• check merge.rs on possible leaks and unoptimized code parts https://github.com/metrico/qryn/blob/master/pyroscope/pprof-bin/src/merge.rs