doc,test: add server.timeout property to http2 public API

Both http and https modules have server.timeout property
in public API. This commit adds documentation section and test
for server.timeout in http2 module, so it becomes consistent
with http and https.

Also improves description of callback argument in documentation
for server.setTimeout().

PR-URL: https://github.com/nodejs/node/pull/31693


Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>