ChatInput: element outline highlighting is inconsistent (input and Credit Limit Reached have outlines, todos don't)

[courtney-free]

Testing microsoft/vscode-internalbacklog#7701

[bhavyaus]

I created the issue while testing using the wrong account!

[cwebster-99]

Would love to get input from @eli-w-king on this! I agree the mix of border types is a bit odd in this. I wonder if we should extend the outer border over all the above chat widgets?

[eli-w-king]

This banner doesn't need a highlight border. Only chat input should be highlighted here.