[Feature Request] I hope el-radio and el-checkbox add slots in border mode to customized

### Existing Component
是

### Component Name
Radio、Checkbox

### Description
希望增加Radio、Checkbox 在border模式下的自定义插槽 ，目前组件只支持单行文字的显示

I hope el-radio and el-checkbox add slots in border mode to customized, at present, the component only supports single line text display

Start by locating the el-radio and el-checkbox components and reading how their border mode currently renders its label content. Check existing component tests and slot patterns before deciding the expected custom-content behavior; done means both bordered components support customized content without breaking their current single-line usage.

Written by the indexing model from the issue text.