ref: merge TooltipPreviewImage and TooltipWidget (#4268)

* merge TooltipPreviewImage and TooltipWidget

* changelog

* add empty line before return

* fix signalholder include

* add changelog for bugfix

* fix custom scaling issue

Co-authored-by: pajlada <rasmus.karlsson@pajlada.com>

CHANGELOG.md

@@ -16,11 +16,13 @@
 - Bugfix: Fixed crash that could occur when changing Tab layout and utilizing multiple windows. (#4248)
 - Bugfix: Fixed text sometimes not pasting properly when image uploader was disabled. (#4246)
 - Bugfix: Fixed text cursor(caret) not showing in open channel dialog. (#4196)
+- Bugfix: Fixed tooltip images not appearing if mouse hovered only first pixel. (#4268)
 - Dev: Remove protocol from QApplication's Organization Domain (so changed from `https://www.chatterino.com` to `chatterino.com`). (#4256)
 - Dev: Ignore `WM_SHOWWINDOW` hide events, causing fewer attempted rescales. (#4198)
 - Dev: Migrated to C++ 20 (#4252, #4257)
 - Dev: Enable LTO for main branch builds. (#4258, #4260)
 - Dev: Removed unused include directives. (#4266)
+- Dev: Removed TooltipPreviewImage. (#4268)
 - Dev: Removed unused operators in `Image` (#4267)
 
 ## 2.4.0