Push enhanced context state to the extension when creating an EnhancedContextPanel

[dominiccooney]

Fixes #1347

Test plan

• Open a clone of the sourcegraph repo
• Start a chat, click Pencil, add github.com/sourcegraph/cody repo, cmd-enter to commit
• Ask "how do local embeddings work", there should be some context results from the cody repo
• Click pencil, add github.com/sourcegraph/handbook repo, cmd-enter to commit
• Click "new chat" button
• Ask "what's the role of an engineering manager?", there should be some context results from the handbook repo
• Click pencil, delete the handbook repo, cmd-enter to commit
• Ask "what's the role of an engineering manager?", there should be no context results from the handbook repo
• Chat history, select the first chat, the repo selector should show the cody and handbook repos
• Chat history, select the second chat, the repo selector should show the cody repo

[pkukielka]

LGTM