chore: enable CLI args filtering and support multiple benchmark classes

[sdwck]

Extracted this change into its own PR.
This replaces Benchmark.Run with Benchmark.FromAssembly.
This brings 2 DX improvements:

• Passing args, it allows running specific benchmarks with dotnet run -c Release --project Benchmarks -- --filter *RemoveCharacters*
• If new benchmark classes are added, they will automatically be picked up

[Antyss77]

Thanks for splitting this out. Tested it on our CI runner (non-interactive), and unfortunately BenchmarkSwitcher.Run(args, config) with empty args doesn't run anything — it just prints the "select a benchmark" prompt and exits, since there's no stdin to read from on a CI runner:

Available Benchmark:
#0 StringExtensionBenchmark
You should select the target benchmark(s)...

Our workflow calls dotnet run -c Release --project Benchmarks/Benchmarks.csproj with no arguments, and it needs to keep running every benchmark and printing the full summary table, exactly like before.

Could you make it default to running everything when no args are passed? Something like:

if (args.Length == 0)
{
    BenchmarkSwitcher.FromAssembly(typeof(StringExtensionBenchmark).Assembly).Run(new[] { "--filter", "*" }, config);
}
else
{
    BenchmarkSwitcher.FromAssembly(typeof(StringExtensionBenchmark).Assembly).Run(args, config);
}

That keeps the CLI filtering benefit for local use while keeping CI behavior identical to what it was before this PR. Happy to merge once that's confirmed working.

[sdwck]

Hey! My bad, accidentally deleted my fork while doing some repository cleanup and it auto-closed the PR. Feel free to just copy paste your if/else snippet and push it to master, it's a great fix, and thanks for the code review!