fix quill global style issue

Author: AJIXuMuK

src/controls/richText/RichText.module.scss

@@ -105,7 +105,7 @@
   width: 100%;
 }
 
-:global {
+:global(.pnp-richtext-quill-container) {
   .ql-toolbar {
     background-color: transparent;
     color: "[theme:neutralLighterAlt, default:#{$ms-color-neutralLighterAlt}]";

src/controls/richText/RichText.tsx

@@ -637,6 +637,7 @@ export class RichText extends React.Component<IRichTextProps, IRichTextState> {
         className={
           css(
             styles.richtext && this.state.editing ? 'ql-active' : null,
+            'pnp-richtext-quill-container',
             this.props.className || null
           ) || null
         }