feat(VAppBar): don't truncate title with shrink-on-scroll

[KaelWD]

Description

Adds a new v-app-bar-title component which uses absolute positioning to avoid
being truncated when there isn't enough space in the main part of the toolbar

closes #12514

Markup:

<template>
  <v-container style="height: 1200px">
    <v-app-bar
      fixed
      shrink-on-scroll
    >
      <v-app-bar-nav-icon />
      <v-app-bar-title>Vuetify.js</v-app-bar-title>
      <v-spacer />
      <v-btn icon>
        <v-icon>mdi-chart-box-outline</v-icon>
      </v-btn>
      <v-btn icon>
        <v-icon>mdi-cog-outline</v-icon>
      </v-btn>
      <v-responsive max-width="260">
        <v-text-field
          class="ml-1"
          dense
          flat
          placeholder="Search Anywhere"
          hide-details
          rounded
          solo-inverted
          prepend-inner-icon="mdi-magnify"
        />
      </v-responsive>
      <v-btn icon>
        <v-icon>mdi-menu</v-icon>
      </v-btn>
    </v-app-bar>
  </v-container>
</template>

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:

• I've added relevant changes to the documentation (applies to new features and breaking changes in core library)