fix(VItemGroup): allow object values and custom comparator

[Tofandel]

Description

Fixes #10571

Motivation and Context

Radio groups with object as values where not properly marked as active because the objects (having different reference) are compared with === instead of deep equality

How Has This Been Tested?

unit test and playground

Markup:

<template>
  <v-container>
    <v-radio-group v-model="radio">
      <v-radio
        label="test 1"
        :value="{test: 1}"
      ></v-radio>
      <v-radio
        label="test 2"
        :value="{test: 2}"
      ></v-radio>
      <v-radio
        label="test 3"
        :value="3"
      ></v-radio>
    </v-radio-group>
  </v-container>
</template>

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