fix(VAutocomplete): fix unable to set default searchInput

[NoahKa0]

resolves #9757

Description

When using a default value in search-input it was reset because VSelect wasn't aware that it was selected. Now when a default value is used, it will be selected when VAutocomplete is created.

Motivation and Context

This change fixes issue #9757.

How Has This Been Tested?

I've tested this manually.

Markup:

<template>
  <v-container>
    <v-autocomplete
      :search-input.sync="search"
      :items="items"
    />
  </v-container>
</template>

<script>
  export default {
    data: () => ({
      search: 'three',
      items: [
        'one',
        'two',
        'three'
      ],
    }),
  }
</script>

Types of changes

• [x] 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:

• [x] The PR title is no longer than 64 characters.
• [x] 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).
• [x] 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)