feat(VTreeview): **rounded**/**shaped** props

[jacekkarczmarczyk]

Motivation and Context

fixes #7614

How Has This Been Tested?

playground

Markup:

<template>
  <div class="ma-5 pa-5">
    <v-treeview v-model="selected" rounded :active="selected" :items="treeItems" color="primary" activatable selectable hoverable />
    <v-divider />
    <v-treeview :items="treeItems" shaped color="red" activatable hoverable open-on-click />
  </div>
</template>

<script>
  export default {
    data: () => ({
      selected: [],
      treeItems: [
          {
            id: 1,
            name: 'Applications:',
            children: [
              { id: 2, name: 'Calendar' },
              {
                id: 3,
                name: 'Chrome',
                children: [
                  { id: 4, name: 'Foo', disabled: true },
                  { id: 5, name: 'Bar' },
                  { id: 6, name: 'Baz' }
                ],
              },
              { id: 7, name: 'Webstorm' }
            ]
          },
          {
            id: 8,
            name: 'Also applications:',
            disabled: true,
            children: [
              { id: 9, name: 'Calendar' },
              { id: 357, name: 'Chrome' },
            ]
          },
        ]
    }),
  }
</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 feature but make 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 breaking 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)

[dsseng]

maybe add docs examples?

[jacekkarczmarczyk]

I'd prefer to add them to the new structure (#7641) to avoid possible merging conflicts. So either I'll update 7641 after merging this PR or I'll add docs to this PR after merging 7641

[codecov]

Codecov Report

Merging #7616 into next will increase coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             next    #7616      +/-   ##
==========================================
+ Coverage   86.93%   86.93%   +<.01%     
==========================================
  Files         326      326              
  Lines        8540     8536       -4     
  Branches     2154     2153       -1     
==========================================
- Hits         7424     7421       -3     
+ Misses       1026     1025       -1     
  Partials       90       90

Impacted Files	Coverage Δ
.../vuetify/src/components/VTreeview/VTreeviewNode.ts	98.66% <ø> (ø)	⬆️
...es/vuetify/src/components/VDataTable/VDataTable.ts	84.24% <0%> (-0.19%)	⬇️
packages/vuetify/src/util/helpers.ts	91.79% <0%> (-0.05%)	⬇️
...es/vuetify/src/components/VSparkline/VSparkline.ts	73.14% <0%> (ø)	⬆️
packages/vuetify/src/components/VInput/VInput.ts	97.18% <0%> (ø)	⬆️
...uetify/src/components/VCheckbox/VSimpleCheckbox.ts	90.47% <0%> (+4.11%)	⬆️

---

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[codecov]

Codecov Report

Merging #7616 into next will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             next    #7616      +/-   ##
==========================================
+ Coverage   86.93%   86.94%   +0.01%     
==========================================
  Files         326      326              
  Lines        8540     8540              
  Branches     2154     2154              
==========================================
+ Hits         7424     7425       +1     
+ Misses       1026     1025       -1     
  Partials       90       90

Impacted Files	Coverage Δ
.../vuetify/src/components/VTreeview/VTreeviewNode.ts	98.66% <ø> (ø)	⬆️
packages/vuetify/src/components/VSelect/VSelect.ts	93.4% <0%> (+0.36%)	⬆️

---

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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