`agent_fast_reply` output missing `intermediate_steps`

When using agent_fast_reply one should be able to return:

a dictionary or
an AgentOutput instance

In the case of a dictionary, if the plugin does not add an intermediate_steps to the output, the Cat errors when building the why here:

core/core/cat/looking_glass/stray_cat.py

Line 412 in 4fe0738

why.intermediate_steps = agent_output.intermediate_steps

It is easily fixed by converting the dict in output from agentfast_reply in an AgentOutput instance, that assigns intermediate_steps automatically empty.
Here the place to convert:

core/core/cat/agents/main_agent.py

Line 55 in 4fe0738

return fast_reply

Fixed in develop