Render tooltips Theia theme aware

[sgraband]

Feature Description:

Currently all of the tooltips in the standard views (e.g. explorer, problems, ...) are rendered using plain HTML. Therefore, the tooltips are styled according to the users global system theme and not the active Theia theme. This can lead to inconsistencies, which frankly do not look nice:

We should investigate, if there are any downsides to using the already exsting HoverService, which would style the tooltips better and would be consistent with the theme.
Another idea would be to investigate whether or not one could mock/fake the system theme so that the tooltips are at least rendered correctly in light/dark theme.
This could also be turned on/off via a setting similar to how it has been done with the tab-bar hover styling.

[mvtec-richter]

The PR #15037 only partially addresses this issue:
The tooltip now follow the dark/light setting of the Theia theme only on Windows and MacOS in the electron application. On Linux changing dark/light mode of an electron application is not implemented in electron. For browser applications, changing the native theme is not possible.