Deduplicate walltime perf symbols, unwind data and debug info across pids

[GuillaumeLagrange]

Merge/deployment

1. Merge feat(runner-shared): add new fields to perf metadata #246 (on top of which this PR is based)
2. Merge the backend PR refering to the changed perf metadata changes
3. Merge this pr and release runner once the changes in the backend are in prod

Content

Since the real deduplicator source of truth is actually the path of the elf file on disk, I settled on

{path_index}__{file_name}.unwind_data
{path_index}__{file_name}.symbols.map

it allows for the filename to be determined by the actual path, without having to either nest all the files, or have to sanitize paths to file name and end up in awkward file-name length limitations

Here's what it looks like on a 1000 iterations report of one simple program

$ ls
0__exec-harness.symbols.map          3__ld-linux-x86-64.so.2.unwind_data  7__nix-ld.symbols.map         perf.metadata
0__exec-harness.unwind_data          4__ld-linux-x86-64.so.2.symbols.map  7__nix-ld.unwind_data         perf.pipedata
1__libm.so.6.symbols.map             4__ld-linux-x86-64.so.2.unwind_data  8__libc.so.6.symbols.map      results
1__libm.so.6.unwind_data             5__libgcc_s.so.1.symbols.map         8__libc.so.6.unwind_data      runner.log
2__graph-benchmark.symbols.map       5__libgcc_s.so.1.unwind_data         9__libgcc_s.so.1.symbols.map
2__graph-benchmark.unwind_data       6__libc.so.6.symbols.map             9__libgcc_s.so.1.unwind_data
3__ld-linux-x86-64.so.2.symbols.map  6__libc.so.6.unwind_data             ExecutionTimestamps.msgpack

[codspeed-hq]

Merging this PR will not alter performance

✅ 4 untouched benchmarks

---

_{Comparing cod-2138-deduplicate-perf-maps-and-unwind_data (82a55b9) with main (5bb49e6)}

[not-matthias]

I think the struct naming can be clarified a bit, I was struggling quite a lot to understand how they map together. Maybe also using custom types for the key that's used in the hashmaps.

The overall logic looks good! Next round should be quick

[not-matthias]

LGTM overall. Just a few minor stylistic comments.

[art049]

Just the naming thing TBD
Otherwise, lgtm! this needs extensive testing before release though