Session: add ability to edit a previously sent message by the user

[fmaclen]

REF #9

• Any message from the User or Assistant will now have an edit button (next to the copy button)
• When clicking the edit button the prompt field will be populated with the content of the message
• If editing a User message, the Run button changes to Save & Run
• In both cases there would also be a Cancel (or Dismiss, Discard) button that makes everything go back to the way it was before clicking Edit
• We can probably use the icon: <Pencil />
• After the message has been updated run a toast.success() notice.

Later we can allow editing assistant messages:

• If editing an Assistant message, the Run button changes the label to Save, once clicked the new edited message should be visible in the session history.
• Assistant messages can only be saved because there is new completion unless the user submits a new prompt after.

[fmaclen]

@GregoMac1 I'm wondering if it makes sense to split this issue in 2 parts: 1- Edit user message behavior 2- Edit assistant message behavior

I think editing the user message is more useful than editing the assistant message, so we can punt that part for later.

[GregoMac1]

@fmaclen I was wondering on what should happen when the user edits a message and clicks Save & Run. Should the old response be deleted and replaced for the new response to the edited message?

[fmaclen]

Should the old response be deleted and replaced for the new response to the edited message?

@GregoMac1 Yeah, that's what I had in mind.