Provide a floating toolbar on autoconfig-file changes to reapply autoconfig

[nailujx86]

IntelliJ supports floating toolbars which can be shown or hidden on demand. One example is the toolbar shown when making changes in a pom.xml of a maven based project.

We could add a similar functionality where a toolbar is shown when an autoconfig file is changed. This toolbar/toolbar-button could reapply autoconfig on click.

Extensionpoint: com.intellij.openapi.editor.toolbar.floating.FloatingToolbarProvider
For usage examples see: https://plugins.jetbrains.com/intellij-platform-explorer/extensions?extensions=com.intellij.editorFloatingToolbarProvider