wip: import-fuchsia tool to import fuchsia traces

[c-cube]

still wip, but promising! I could import spans from my sample trace. Reading arguments is not there yet, and lots of metadata are ignored.

See: https://fuchsia.dev/fuchsia-src/reference/tracing/trace-format

[anthofoxo]

Confirmed, successful build on windows, vs2022

[wolfpld]

Please add some documentation about this to the manual and update the CI build scripts at .github/workflows/.

[c-cube]

done!