consider adding a default negotiate timeout

[jmayclin]

Problem:

Currently consumers of s2n-tls are responsible for implementing reasonable timeouts to deal with malicious behavior.

Solution:

s2n-tls could implement a reasonable timeout (e.g. 10 seconds) to make default usage of s2n-tls more resilient and efficient. s2n-quic has similar protections in place.

Requirements / Acceptance Criteria:

Customers that write naive event loops without timeouts should have some basic level of protection against simple slow-loris style attacks.

Out of scope:

Even if this is infeasible for the C library due to backwards compatibility concerns, we might consider doing it for a smaller subset of customers. Perhaps just the rust bindings.