Add typo detection to CI (#4107)

Adding the typos crate to our CI will take some doing, as we have
several tests which rely on typos in various ways (e.g. checking state
as the user types), but I thought I'd take a first stab at fixing what
it finds.

Release Notes:

- N/A

crates/copilot_ui/src/sign_in.rs

@@ -96,7 +96,7 @@ impl CopilotCodeVerification {
             .items_center()
             .child(Headline::new("Use Github Copilot in Zed.").size(HeadlineSize::Large))
             .child(
-                Label::new("Using Copilot requres an active subscription on Github.")
+                Label::new("Using Copilot requires an active subscription on Github.")
                     .color(Color::Muted),
             )
             .child(Self::render_device_code(data, cx))
@@ -139,7 +139,7 @@ impl CopilotCodeVerification {
                 "You can enable Copilot by connecting your existing license once you have subscribed or renewed your subscription.",
             ).color(Color::Warning))
             .child(
-                Button::new("copilot-subscribe-button", "Subscibe on Github")
+                Button::new("copilot-subscribe-button", "Subscribe on Github")
                     .full_width()
                     .on_click(|_, cx| cx.open_url(COPILOT_SIGN_UP_URL)),
             )