MM-23568: Add rudder to server diagnostics. (#14151)

* MM-23568: Add rudder to server diagnostics.

* Add unit test.

* Go mod tidy.

* CSP Header fix.

* Fix review comments.

* Update web/handlers.go

Co-Authored-By: Jesse Hallam <jesse.hallam@gmail.com>

* Partially address review comments.

* fix tests.

* Finish implementing review suggestions and then fixing tests.

* Fix CSP Header tests.

Co-authored-by: Jesse Hallam <jesse.hallam@gmail.com>

web/handlers_test.go

@@ -296,7 +296,7 @@ func TestHandlerServeCSPHeader(t *testing.T) {
 		response := httptest.NewRecorder()
 		handler.ServeHTTP(response, request)
 		assert.Equal(t, 200, response.Code)
-		assert.Equal(t, response.Header()["Content-Security-Policy"], []string{"frame-ancestors 'self'; script-src 'self' cdn.segment.com/analytics.js/"})
+		assert.Equal(t, response.Header()["Content-Security-Policy"], []string{"frame-ancestors 'self'; script-src 'self' cdn.rudderlabs.com cdn.segment.com/analytics.js/"})
 	})
 
 	t.Run("static, with subpath", func(t *testing.T) {
@@ -333,7 +333,7 @@ func TestHandlerServeCSPHeader(t *testing.T) {
 		response := httptest.NewRecorder()
 		handler.ServeHTTP(response, request)
 		assert.Equal(t, 200, response.Code)
-		assert.Equal(t, response.Header()["Content-Security-Policy"], []string{"frame-ancestors 'self'; script-src 'self' cdn.segment.com/analytics.js/"})
+		assert.Equal(t, response.Header()["Content-Security-Policy"], []string{"frame-ancestors 'self'; script-src 'self' cdn.rudderlabs.com cdn.segment.com/analytics.js/"})
 
 		// TODO: It's hard to unit test this now that the CSP directive is effectively
 		// decided in Setup(). Circle back to this in master once the memory store is
@@ -348,7 +348,7 @@ func TestHandlerServeCSPHeader(t *testing.T) {
 		response = httptest.NewRecorder()
 		handler.ServeHTTP(response, request)
 		assert.Equal(t, 200, response.Code)
-		assert.Equal(t, response.Header()["Content-Security-Policy"], []string{"frame-ancestors 'self'; script-src 'self' cdn.segment.com/analytics.js/"})
+		assert.Equal(t, response.Header()["Content-Security-Policy"], []string{"frame-ancestors 'self'; script-src 'self' cdn.rudderlabs.com cdn.segment.com/analytics.js/"})
 		// TODO: See above.
 		// assert.Contains(t, response.Header()["Content-Security-Policy"], "frame-ancestors 'self'; script-src 'self' cdn.segment.com/analytics.js/ 'sha256-tPOjw+tkVs9axL78ZwGtYl975dtyPHB6LYKAO2R3gR4='", "csp header incorrectly changed after subpath changed")
 	})