Add benchmarks for MapAction

[halter73]

Create a suite of benchmarks at aspnet/benchmarks to cover most common user scenarios involving MapAction so we can start comparing perf over time vs middleware and normal MVC controllers on https://aka.ms/aspnet/benchmarks. We can start by adding MapAction versions of existing benchmarks:

• TechEmpower JSON serialization
• TechEmpower Fortunes

Eventually, we should add more scenarios to exercise specific code paths around model binding, input formatters, action filters etc... If there are no equivalent MVC benchmarks for these things yet we should add them for comparison.