feat: use different public-key length certs for TLS

[DeagleGross]

I've noticed, that certificate length heavily contributes to the TLS speed (4096 bit vs 2048 bit). I have seen http.sys using 2048 bit length cert, and kestrel using a testCert.pfx which is 4096 bit length, meaning tests are unfair.

Besides updating certificates on the machines, I prepared a separate nginx test (with a possibility to specify a cert length) and updated http.sys + kestrel benchmarks to have such a parameter (http.sys now issues a cert before each run and kestrel uses pre-created certs)

Here are the RPS values for some random run on a server using different cert lengths

Cert length \ Server	Nginx	Kestrel	Http.Sys
2048	2,167	1436	1250-1450 (depending on EC curve)
4096	491	443	439

[sebastienros]

fyi we already have some docker file and config and certs using nginx. At least if there is a reason to create a new one then some things should be reused: https://github.com/aspnet/Benchmarks/blob/main/docker/nginx/nginx-https.conf

[sebastienros]

Can you check there aren't secrets / keys to add in the configuration files to prevent credscan from blocking internal merges?