[ZEPPELIN-6384] Fix dropdown menu item links not clickable in full area

### What is this PR for?

#### Summary

- Fixed dropdown menu items in header where only text was clickable instead of the full item area
- Changed routerLinkActive to nzMatchRouter for proper NG-ZORRO integration
- Added CSS pseudo-element to expand clickable area of anchor tags

#### Cause

- Likely due to NG-ZORRO dropdown menu item anchor tag style changes that reduced the clickable area to just the text content.

#### Changes

- Updated `header.component.html`: Replace `routerLinkActive` with `nzMatchRouter` directive
- Updated `global.less`: Add `::before` pseudo-element to `.ant-dropdown-menu-item > a` to expand clickable area using absolute positioning

### What type of PR is it?
Bug Fix

### What is the Jira issue?
https://issues.apache.org/jira/browse/ZEPPELIN-6384

### Questions:
* Does the license files need to update? No
* Is there breaking changes for older versions? No
* Does this needs documentation? No

Closes #5124 from tbonelee/fix-dropdown-link.

Signed-off-by: ChanHo Lee <[email protected]>
(cherry picked from commit b4193a0)
Signed-off-by: ChanHo Lee <[email protected]>

Author: tbonelee

zeppelin-web-angular/src/app/share/header/header.component.html

@@ -52,19 +52,19 @@
       <ul nz-menu>
         <li nz-menu-item (click)="about()">About Zeppelin</li>
         <li nz-menu-divider></li>
-        <li nz-menu-item routerLinkActive="ant-dropdown-menu-item-selected">
+        <li nz-menu-item nzMatchRouter>
           <a [routerLink]="['/interpreter']">Interpreter</a>
         </li>
-        <li nz-menu-item routerLinkActive="ant-dropdown-menu-item-selected">
+        <li nz-menu-item nzMatchRouter>
           <a [routerLink]="['/notebook-repos']">Notebook Repos</a>
         </li>
-        <li nz-menu-item routerLinkActive="ant-dropdown-menu-item-selected">
+        <li nz-menu-item nzMatchRouter>
           <a [routerLink]="['/credential']">Credential</a>
         </li>
-        <!--        <li nz-menu-item routerLinkActive="ant-dropdown-menu-item-selected">-->
+        <!--        <li nz-menu-item nzMatchRouter>-->
         <!--          <a [routerLink]="['/helium']">Helium</a>-->
         <!--        </li>-->
-        <li nz-menu-item routerLinkActive="ant-dropdown-menu-item-selected">
+        <li nz-menu-item nzMatchRouter>
           <a [routerLink]="['/configuration']">Configuration</a>
         </li>
         <ng-container *ngIf="ticketService.ticket.principal !== 'anonymous'">

zeppelin-web-angular/src/styles/global.less

@@ -115,6 +115,14 @@
   }
 }
 
+// Fix `a` tag in nz-dropdown-menu to be clickable with full width
+.ant-dropdown-menu-item > a::before {
+  position: absolute;
+  inset: 0;
+  background-color: transparent;
+  content: '';
+}
+
 //.view-lines {
 //  .view-line {
 //    &:first-child {