Handle supermaven account status messages (#14749)

Sets the account status state to allow the Supermaven button to move out
of the "Supermaven is initializing..." state. We also need to add the
ability to sign out and change tiers but I will do that in a separate
PR.

Release Notes:

- Improved Supermaven status messages
([#12715](https://github.com/zed-industries/zed/issues/12715)).

crates/supermaven/src/supermaven.rs

@@ -354,7 +354,11 @@ impl SupermavenAgent {
                     None => AccountStatus::Ready,
                 };
             }
+            SupermavenMessage::ActivationSuccess => {
+                self.account_status = AccountStatus::Ready;
+            }
             SupermavenMessage::ServiceTier { service_tier } => {
+                self.account_status = AccountStatus::Ready;
                 self.service_tier = Some(service_tier);
             }
             SupermavenMessage::Response(response) => {