feat: add support for share menu on macOS (#25629)

docs/api/share-menu.md

@@ -0,0 +1,45 @@
+## Class: ShareMenu
+
+> Create share menu on macOS.
+
+Process: [Main](../glossary.md#main-process)
+
+The `ShareMenu` class creates [Share Menu][share-menu] on macOS, which can be
+used to share information from the current context to apps, social media
+accounts, and other services.
+
+For including the share menu as a submenu of other menus, please use the
+`shareMenu` role of [`MenuItem`](menu-item.md).
+
+### `new ShareMenu(sharingItem)`
+
+* `sharingItem` SharingItem - The item to share.
+
+Creates a new share menu.
+
+### Instance Methods
+
+The `shareMenu` object has the following instance methods:
+
+#### `shareMenu.popup([options])`
+
+* `options` PopupOptions (optional)
+  * `browserWindow` [BrowserWindow](browser-window.md) (optional) - Default is the focused window.
+  * `x` Number (optional) - Default is the current mouse cursor position.
+    Must be declared if `y` is declared.
+  * `y` Number (optional) - Default is the current mouse cursor position.
+    Must be declared if `x` is declared.
+  * `positioningItem` Number (optional) _macOS_ - The index of the menu item to
+    be positioned under the mouse cursor at the specified coordinates. Default
+    is -1.
+  * `callback` Function (optional) - Called when menu is closed.
+
+Pops up this menu as a context menu in the [`BrowserWindow`](browser-window.md).
+
+#### `shareMenu.closePopup([browserWindow])`
+
+* `browserWindow` [BrowserWindow](browser-window.md) (optional) - Default is the focused window.
+
+Closes the context menu in the `browserWindow`.
+
+[share-menu]: https://developer.apple.com/design/human-interface-guidelines/macos/extensions/share-extensions/