This PR adds a new rpc JSON API to create a new chat and return the newly created chat ID, which is very useful for Cody Web client (waiting for the transcript event might be tricky especially because it event won't be sent if no transcription hasn't been published yet)
Change is safe to merge since it's only web-specific and has no effect on other clients.
Part of SRCH-632
This is the one of PRs that come from the bigger change we did for Cody Web in this main PR https://github.com/sourcegraph/cody/pull/4605
This PR adds a new rpc JSON API to create a new chat and return the newly created chat ID, which is very useful for Cody Web client (waiting for the transcript event might be tricky especially because it event won't be sent if no transcription hasn't been published yet)
Change is safe to merge since it's only web-specific and has no effect on other clients.
Test plan