feat: Update previous and next unit navigation buttons design (#1617)

* feat: Update previous and next unit navigation buttons design

* feat: add unit test

* feat: move unit navigation to be inline with unit title

src/plugin-slots/NextUnitTopNavTriggerSlot/index.tsx

@@ -5,7 +5,6 @@ import { PluginSlot } from '@openedx/frontend-plugin-framework';
 import NextButton from '../../courseware/course/sequence/sequence-navigation/generic/NextButton';
 
 interface Props {
-  courseId: string | '';
   disabled: boolean;
   buttonText: string | '';
   nextLink: string;
@@ -14,10 +13,10 @@ interface Props {
   onClickHandler: () => void;
   variant: string;
   buttonStyle: string;
+  isAtTop: boolean;
 }
 
 export const NextUnitTopNavTriggerSlot : React.FC<Props> = ({
-  courseId,
   disabled,
   buttonText,
   nextLink,
@@ -25,11 +24,11 @@ export const NextUnitTopNavTriggerSlot : React.FC<Props> = ({
   onClickHandler,
   variant,
   buttonStyle,
+  isAtTop,
 }) => (
   <PluginSlot
     id="next_unit_top_nav_trigger_slot"
     pluginProps={{
-      courseId,
       disabled,
       buttonText,
       nextLink,
@@ -37,6 +36,7 @@ export const NextUnitTopNavTriggerSlot : React.FC<Props> = ({
       onClickHandler,
       variant,
       buttonStyle,
+      isAtTop,
     }}
   >
     <NextButton
@@ -47,6 +47,7 @@ export const NextUnitTopNavTriggerSlot : React.FC<Props> = ({
         nextLink,
         disabled,
         buttonText,
+        isAtTop,
       }}
     />
   </PluginSlot>