fix(components): include mode classes on components for use in shadow (#17838)

- removes mode-less component classes from the internal CSS, use element instead
- adds mode specific classes `md` or `ios` for styling inside of shadow components
- adds e2e test that verifies mode classes exist on all ionic components, plus checks for specific classes that the components need for internal styling

fixes #17608

core/src/components/checkbox/checkbox.tsx

@@ -137,6 +137,7 @@ export class Checkbox implements ComponentInterface {
       'aria-labelledby': labelId,
       class: {
         ...createColorClasses(color),
+        [`${this.mode}`]: true,
         'in-item': hostContext('ion-item', el),
         'checkbox-checked': checked,
         'checkbox-disabled': disabled,