fix(VColorPicker): use theme color for color-picker inputs

[obennaci]

fix #12169

Description

fixes #12169

How Has This Been Tested?

Visually

Markup:

<template>
  <v-container>
    <v-color-picker class="ma-2"/>
    <v-color-picker
      class="ma-2"
      dark
    />
  </v-container>
</template>

<script>
  export default {
    data: () => ({
    //
    }),
  }
</script>

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Improvement/refactoring (non-breaking change that doesn't add any features but makes things better)

Checklist:

• The PR title is no longer than 64 characters.
• The PR is submitted to the correct branch (master for bug fixes and documentation updates, dev for new features and backwards compatible changes and next for non-backwards compatible changes).
• My code follows the code style of this project.
• I've added relevant changes to the documentation (applies to new features and breaking changes in core library)