Finish making shell/platform/linux/... compatible with .clang-tidy. (#48297)

Author: matanlurey

shell/platform/linux/key_mapping.h

@@ -49,6 +49,7 @@ typedef struct {
   bool mandatory;
 } LayoutGoal;
 
+// NOLINTNEXTLINE(readability-identifier-naming)
 extern const std::vector<LayoutGoal> layout_goals;
 
 #endif  // KEYBOARD_MAP_H_

shell/platform/linux/testing/mock_text_input_view_delegate.h

@@ -20,6 +20,7 @@ class MockTextInputViewDelegate {
   MockTextInputViewDelegate();
   ~MockTextInputViewDelegate();
 
+  // NOLINTNEXTLINE(google-explicit-constructor)
   operator FlTextInputViewDelegate*();
 
   MOCK_METHOD(void,