feat(theme): theme prop is now available on each component

[nekosaur]

Description

add theme prop to each component so that it can override provided value and start new context for it and all children

NOTE this will add two computed variables for every component. there is no way of conditionally providing values

fixes #13288

TODO

• Make sure documentation is up-to-date and correct

Motivation and Context

How Has This Been Tested?

playground

Markup:

<template>
  <v-app class="fill-height">
    <v-card :theme="theme" title="foo" subtitle="bar">
      <v-btn @click="theme = theme === 'light' ? 'dark' : 'light'">toggle</v-btn>
    </v-card>

    <v-card theme="dark" title="foo" subtitle="foo" color="purple-darken-2" append-icon="$close" />

    <v-theme-provider theme="dark" with-background>
      <v-card title="foo" subtitle="bar" class="ma-10" />
    </v-theme-provider>

    <v-card theme="dark" title="first">
      <v-card theme="light" title="second" class="ma-5">
        <v-card theme="dark" title="third" class="ma-5" />
      </v-card>
    </v-card>

    <v-card theme="dark" title="foo" subtitle="bar">
      <v-theme-provider theme="light">
        <v-card-actions>
          <v-btn color="primary">foo</v-btn>
        </v-card-actions>
      </v-theme-provider>
    </v-card>
  </v-app>
</template>

<script>
  import { ref } from 'vue'

  export default {
    name: 'Playground',
    setup () {
      const theme = ref('light')

      return { theme }
    },
  }
</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)

[johnleider]

Code looks good. Feedback is here https://discord.com/channels/340160225338195969/519331123239583755/847520162365833216

[glen-84]

Closes #13288. (?)

[johnleider]

Looks good. Any api-generator updates that need to be made?