Support CC migrate-installer path (#35717)

If we can't find CC in the PATH, we'll now fall back to a known local
install path.

Release Notes:

- N/A

crates/agent_servers/src/gemini.rs

@@ -48,7 +48,7 @@ impl AgentServer for Gemini {
             })?;
 
             let Some(command) =
-                AgentServerCommand::resolve("gemini", &[ACP_ARG], settings, &project, cx).await
+                AgentServerCommand::resolve("gemini", &[ACP_ARG], None, settings, &project, cx).await
             else {
                 anyhow::bail!("Failed to find gemini binary");
             };