`fake` agent allowing timeouts or exceptions,

[jamesbraza]

Easier to read diff: https://github.com/Future-House/paper-qa/compare/standard-rollouts?expand=1&w=1

This PR:

• Creates a helper function run_with_timeout_failure that runs a rollout with AgentStatus.TRUNCATED (timeout) or AgentStatus.FAIL (Exception) support
• Moves all three runners (fake, aviary, LDP) to use it
  • Now the fake agent supports timeouts or failures 🥳
• Adds AgentStatus.TRUNCATED support for the LDP agent runner