feat(Slider): Add slot to pass through tooltip content

[dan-hale]

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Customize appearence of value in slider tooltip, such as with NumberFlow:

<USlider v-model="selected" tooltip v-slot="text">
  <NumberFlow :value="text" :format="{ style: 'decimal', trailingZeroDisplay: 'stripIfInteger' }" />
</USlider>

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

Concerns

1. I'm not sure what steps are necessary to properly add this to the documentation
2. On lines 136-138, I place the slot in template with v-if. I'm unsure if this is the best way to do this. I'm trying ensure when no slot is passed, the default tooltip content is used.