Benchmark wrt input size

[jtec]

Makes the PRX bechmark a bit more interesting by

• Profiling execution time across a range of input obs file durations
• Profiling peak RAM usage
• Plotting execution time per function, making it easy to see how individual functions scale (we like O(n) - and O(1) even more ;) and where prx spends its time (spoiler alert: parsing the nav file)

Example outcome with a 3h, 1Hz input file

[plutonheaven]

memray does not work on Windows, so I added some fixes to ignore it on Windows. The benchmark will be less complete...

I also corrected a call to prx_root_directory which has just been changed to prx_src_directory and also made a small change to OS-independent path.

[jtec]

@plutonheaven Thanks for testing on Windows and making the fix!