chore: move /gitauth to /externalauth on the frontend (#9954)

* chore: move `/gitauth` to `/externalauth` on the frontend

This actually took a lot more jank than anticipated,
so I wanted to split this up before adding the ability
to embed new providers.

* Rename FE

* Fix em' up

* Fix linting error

* Fix e2e tests

* chore: update helm golden files

coderd/tracing/httpmw.go

@@ -26,7 +26,7 @@ func Middleware(tracerProvider trace.TracerProvider) func(http.Handler) http.Han
 		"/api/**",
 		"/@*/*/apps/**",
 		"/%40*/*/apps/**",
-		"/gitauth/*/callback",
+		"/externalauth/*/callback",
 	}.MustCompile()
 
 	var tracer trace.Tracer

coderd/tracing/httpmw_test.go

@@ -59,7 +59,7 @@ func Test_Middleware(t *testing.T) {
 			{"/%40hi/hi/apps/hi", true},
 			{"/%40hi/hi/apps/hi/hi", true},
 			{"/%40hi/hi/apps/hi/hi", true},
-			{"/gitauth/hi/callback", true},
+			{"/externalauth/hi/callback", true},
 
 			// Other routes that should not be collected.
 			{"/index.html", false},