refactor(component): refactor the implementation of Button and IconButton (#7716)

## Button
- Remove props withoutHoverStyle
   refactor hover impl with independent layer, so that hover-color won't affect the background even if is overridden outside
- Update `type` (renamed to `variant`):
  - remove `processing` and `warning`
  - rename `default` with `secondary`
- Remove `shape` props
- Remove `icon` and `iconPosition`, replaced with `prefix: ReactNode` and `suffix: ReactNode`
- Integrate tooltip for more convenient usage
- New Storybook document
- Focus style

## IconButton
- A Wrapper base on `<Button />`
- Override Button size and variant
  - size: `'12' | '14' | '16' | '20' | '24' | number`
     These presets size are referenced from the design system.
  - variant:  `'plain' | 'solid' | 'danger' | 'custom'`
- Inset icon via Button 's prefix

## Fix
- fix some button related issues
- close AF-1159, AF-1160, AF-1161, AF-1162, AF-1163, AF-1158, AF-1157

## Storybook

![CleanShot 2024-08-03 at 14.57.20@2x.png](https://graphite-user-uploaded-assets-prod.s3.amazonaws.com/LakojjjzZNf6ogjOVwKE/f5a76110-35d0-4082-a940-efc12bed87b0.png)

packages/frontend/component/src/ui/loading/loading.tsx

@@ -1,9 +1,10 @@
 import { assignInlineVars } from '@vanilla-extract/dynamic';
 
+import { withUnit } from '../../utils/with-unit';
 import { loading, speedVar } from './styles.css';
 
 export interface LoadingProps {
-  size?: number;
+  size?: number | string;
   speed?: number;
   progress?: number;
 }
@@ -13,11 +14,13 @@ export const Loading = ({
   speed = 1.2,
   progress = 0.2,
 }: LoadingProps) => {
+  // allow `string` such as `16px` | `100%` | `1em`
+  const sizeWithUnit = size ? withUnit(size, 'px') : '16px';
   return (
     <svg
       className={loading}
-      width={size ? `${size}px` : '16px'}
-      height={size ? `${size}px` : '16px'}
+      width={sizeWithUnit}
+      height={sizeWithUnit}
       viewBox="0 0 24 24"
       fill="none"
       xmlns="http://www.w3.org/2000/svg"