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/tab-button/tab-button.tsx

@@ -96,6 +96,7 @@ export class TabButton implements ComponentInterface {
       'aria-selected': selected ? 'true' : null,
       'id': tab !== undefined ? `tab-button-${tab}` : null,
       class: {
+        [`${this.mode}`]: true,
         'tab-selected': selected,
         'tab-disabled': disabled,
         'tab-has-label': hasLabel,