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/infinite-scroll/infinite-scroll.tsx

@@ -1,10 +1,13 @@
 import { Component, ComponentInterface, Element, Event, EventEmitter, EventListenerEnable, Listen, Method, Prop, QueueApi, State, Watch } from '@stencil/core';
 
+import { Mode } from '../../interface';
+
 @Component({
   tag: 'ion-infinite-scroll',
   styleUrl: 'infinite-scroll.scss'
 })
 export class InfiniteScroll implements ComponentInterface {
+  mode!: Mode;
 
   private thrPx = 0;
   private thrPc = 0;
@@ -212,6 +215,7 @@ export class InfiniteScroll implements ComponentInterface {
   hostData() {
     return {
       class: {
+        [`${this.mode}`]: true,
         'infinite-scroll-loading': this.isLoading,
         'infinite-scroll-enabled': !this.disabled
       }