* Move color values to constant
* Fix MonacoPreview flickering on file selection and resizing
* Fix MarkdownPreview flickering on file selection and resizing
* Fix SvgPreview flickering on file selection and resizing
* Create Settings class and standardize background setting for MarkdownPreview
* Replace ColorTranslator.FromHtml with Color.FromArgb for constant color settings
* Use existing SetBackground
* Remove duplicate GetTheme function
* Update src/modules/previewpane/MarkdownPreviewHandler/Settings.cs
* SvgPreviewControl: Add checkered background so that white .svg are visible
* SvgPreviewControl: Move preview generation logic into own class
* SvgPreviewControl: Add possibility to configure background of svg preview pane via the settings ui
* SvgPreviewControl: Take user configuration into consideration when generating svg preview
* SvgPreviewControl: Do not generate preview file, if the actual size is under the 2mb limiation of WebView2
* SvgPreviewControl: Introduce SvgPreviewColorMode enumeration instead of using magic values
* SvgPreviewControl: Add additional checkered pattern shades
* SvgPreviewControl: Use newly introduced enums as default values