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/button/button.tsx

@@ -148,6 +148,7 @@ export class Button implements ComponentInterface {
       'aria-disabled': disabled ? 'true' : null,
       class: {
         ...createColorClasses(color),
+        [`${this.mode}`]: true,
         [buttonType]: true,
         [`${buttonType}-${expand}`]: expand !== undefined,
         [`${buttonType}-${size}`]: size !== undefined,