ApplicationResourceButton: switch to individual ToolTip instances
We currently use a shared tooltip ostensibly to save memory, but the shared opening/closing conditions cause the tooltips to close too early when the cursor has hovered over more then one button by the time it comes to rest on a different one.
To fix around this in the simplest way, let's switch to give each button a unique ToolTip instance. In testing, there is no appreciable increase in memory usage.
BUG: 456129 FIXED-IN: 5.25.3