Context Attachment Should be Configurable by Chat Participants

[amitjoshi438]

Currently even when chat participant is not using the context, the option to attach context is there. I think it can be misleading for users as users would believe that attached context will be used but participant is not actually referring to it.

If we can have some control where after using @Participant, based on configs attachments option can be enabled/disabled.

cc: @isidorn @roblourens

[amitjoshi438]

Also, since the chat variables are global it does help in getting the context but if not used by participants adds handling overhead to remove the #variable from the prompt, again can become confusing for user.