Add implementation of currently non-existent BehaviorRules `max_response_time_ms` field.

[LarryOsterman]

There are many places in the tree where the non-existent max_response_time_ms field is referenced:

docs/GETTING-STARTED.md
examples/code-explainer/tasks/explain-js-async.yaml
examples/code-explainer/tasks/explain-list-comprehension.yaml
examples/code-explainer/tasks/explain-python-recursion.yaml
examples/code-explainer/tasks/explain-sql-join.yaml
site/src/content/docs/getting-started.mdx
site/src/content/docs/guides/eval-yaml.mdx
site/src/content/docs/reference/schema.mdx

Which is used to reference the non-existent MaxResponseTime behavior constraint:

   behavior:
     max_tool_calls: 5
    max_response_time_ms: 30000

These were removed because the constraint is not implemented, however it seems like a similar construct which is seconds based is a useful construct to have, so support for this construct should be added.