Prefill AI Chat with search query

[Bunn]

Task/Issue URL: https://app.asana.com/0/1204167627774280/1208991512395320/f

Description:
When opening AI Chat from the address bar, pre-fill it with the SERP query

Steps to test this PR:

1. Make sure you're set as internal user
2. Go to the SERP, open AI Chat from the address bar button
3. Validate that we're pre-filling the AI Chat with the same query
4. Open AI Chat from the browsing menu button (the ... icon)
5. Validate that we're NOT pre-filling the AI Chat with the same query

[afterxleep]

LGTM, a couple nits in code.

It worked fine in the first search, but if I go back to SERP and search for something else, it does not pre-fill once I go back to AI Chat. Is that expected?

[afterxleep]

LGTM, just a few nits