Add configurable capping for values of H2 `MAX_HEADER_LIST_SIZE` settings frames

[lorban]

Jetty version(s)
12.0.x

Enhancement Description
Currently, HTTP2Session.configure() does not cap the values of the MAX_HEADER_LIST_SIZE settings frames.

We should add new config settings to control this capping.

[sbordet]

MAX_FRAME_SIZE does not need capping, because it is only used for sanity checks.

But MAX_HEADER_LIST_SIZE must be capped because it is used for allocating buffers.

[lorban]

@sbordet thanks, I've updated both the title and the description to reflect this.