Added color options for highlighting search terms

Summary:
This diff builds on the previous ones by enabling other colors to be used as highlights for the search terms. Current color options are: yellow(default), red, blue, green. Possible extensions to this feature could include allow the user to enter a custom hex-color string and use that as the highlight color.

Changelog: DataTable will now have option to have its search terms highlighted in the search results by toggling and customizing the highlight colors in the menu bar

Reviewed By: mweststrate

Differential Revision: D37383163

fbshipit-source-id: c81e383c0570ef5efbf3171b92b81a8fb2e55ea7

desktop/flipper-plugin/src/ui/elements-inspector/elements.tsx

@@ -118,7 +118,7 @@ class PartialHighlight extends PureComponent<{
   content: string;
 }> {
   static HighlightedText = styled.span<{selected: boolean}>((props) => ({
-    backgroundColor: theme.searchHighlightBackground,
+    backgroundColor: theme.searchHighlightBackground.yellow,
     color: props.selected ? `${theme.textColorPrimary} !important` : 'auto',
   }));