Issue #3521905: Rename Agent Instructions and add System Prompt
changes:
- Rename the System Prompt to Agent Instructions in the form, but keep the data name.
- Add a System Prompt called secured_system_prompt in the configuration/entity.
- Hide the System Prompt from the form, unless you set $settings['show_secured_ai_agent_system_prompt'].
- Add the token for the agent_instructions into the System Prompt.