Add performance tests to PR actions

[carsonRadtke]

It is important to maintain performance parity to std::span (at the very least when Safe Buffers are enabled). In order to track this, we should have performance tests between std::span and gsl::span for the latest standard library implementation across Clang, GCC, and MSVC.

@galenelias put together small benchmark comparing the two implementations on various workloads. They have been attached for convenience and provide a good starting point.

span_bench.zip

[SOrtiz1967]

Hi @carsonRadtke! I'm a student learning about open source and CI/CD. I would love to work on this issue and help integrate these performance tests into the PR actions. Could you assign it to me?

[carsonRadtke]

@SOrtiz1967 Done! Let me know if you need any additional guidance.

[Gafoor2005]

Hi, should I keep the attached benchmark code as-is and use it as the baseline for the PR benchmark job? since the benchmark uses C++20 features, should the benchmark workflow target only the latest supported compiler/toolset versions?

[carsonRadtke]

@Gafoor2005 - If possible, we'd like the benchmarks to be compatible with all support compilers and compiler versions. Modifications to the attached benchmark code may be necessary.

FYI, @SOrtiz1967 claimed this bug a couple weeks ago, but I haven't seen any movement. I will unassign and open this up to anybody.