feat(editor): add highlighter (#10573)

Closes: [BS-2909](https://linear.app/affine-design/issue/BS-2909/新增highlighter)

### What's Changed!

Currently the highlighter tool is very similar to brush, but for the future, it's a standalone module.

* Added `Highlighter` element model
* Added `Highlighter` tool
* Added `Highlighter` entry to the global toolbar

blocksuite/affine/model/src/themes/default.ts

@@ -124,6 +124,8 @@ export const DefaultTheme: Theme = {
   shapeFillColor: Medium.Yellow,
   connectorColor: Medium.Grey,
   noteBackgrounColor: NoteBackgroundColorMap.White,
+  // 50% transparent `Default.black`
+  hightlighterColor: { dark: '#ffffff80', light: '#00000080' },
   Palettes,
   ShapeTextColorPalettes,
   NoteBackgroundColorMap,

blocksuite/affine/model/src/themes/types.ts

@@ -21,6 +21,7 @@ export const ThemeSchema = z.object({
   shapeFillColor: ColorSchema,
   connectorColor: ColorSchema,
   noteBackgrounColor: ColorSchema,
+  hightlighterColor: ColorSchema,
 
   // Universal color palettes
   Palettes: z.array(PaletteSchema),