fix: Preserve tray tooltip when showing notifications

[danielchalmers]

Fixes a regression where setting ToolTipText before ForceCreate() can be lost as the visible hover tooltip if ShowNotification(...) is called immediately after the tray icon is created.

Repro

_trayIcon = (TaskbarIcon)resources["TrayIcon"];
_trayIcon.ToolTipText = "Test";
_trayIcon.ForceCreate();
_trayIcon.ShowNotification("Test", "This stops the tooltip from showing");

Then try hovering the tray icon.

Codex explanation

The tooltip is assigned before ForceCreate(), and Create() sends it to Shell_NotifyIcon with NIF_TIP. The problem is the immediately following notification update: ShowNotification(...) sends another NIM_MODIFY with NIF_INFO, but previously did not include the current tooltip fields. Explorer can then stop showing the hover tooltip until the tooltip is written again.

This change preserves the current tooltip state during the notification modify call by sending the cached tooltip text with NIF_TIP, and carrying NIF_SHOWTIP when UseStandardTooltip is enabled.