Description

fixes #14975

Motivation and Context

VIcon was not centered in VBtn in VSystemBar.

How Has This Been Tested?

visually

Markup:

<template>
  <v-container>
    <v-system-bar
      dark
      color="primary"
    >
      <v-btn icon class="red">
        <v-icon>mdi-wifi-strength-4</v-icon>
      </v-btn>
    </v-system-bar>
  </v-container>
</template>

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