fix: display useful plugins tab only if user can install/activate plugins (#3662)

* display useful plugins tab only if user can install/activate plugins

* Apply suggestion from @bfintal

---------

Co-authored-by: Benjamin Intal <bfintal@gmail.com>

Author: kaeizen

src/welcome/index.php

@@ -206,10 +206,12 @@ public static function print_tabs() {
 					</a>
 				<?php } ?>
 
-				<a class="s-tab <?php echo $screen->base === 'stackable_page_stackable-useful-plugins' ? 's-active' : '' ?>"
-					href="<?php echo admin_url( 'admin.php?page=stackable-useful-plugins' ) ?>">
-					<span><?php _e( 'Useful Plugins', STACKABLE_I18N ) ?></span>
-				</a>
+				<?php if ( current_user_can( 'install_plugins' ) && current_user_can( 'activate_plugins' ) ) { ?>
+					<a class="s-tab <?php echo $screen->base === 'stackable_page_stackable-useful-plugins' ? 's-active' : '' ?>"
+						href="<?php echo admin_url( 'admin.php?page=stackable-useful-plugins' ) ?>">
+						<span><?php _e( 'Useful Plugins', STACKABLE_I18N ) ?></span>
+					</a>
+				<?php } ?>
 
 			</div>
 			<?php