Allow HTTP/2 rate control to mitigate HTTP/2 floods (CVE-2023-44487)

[sbordet]

Jetty version(s)
10+

Enhancement Description
Review HTTP/2 rate control in light of CVE-2023-44487, possibly incrementing the default rate.

(in case github/advisory-database#2869 isn't fixed, use top level link https://nvd.nist.gov/vuln/detail/CVE-2023-44487)