fix(VCalendar): add aria roles to monthly calendar

[knknk98]

Description

fixes #14604

add "role" to monthly calendar

• add role="grid" to v-calendar
• add role="row" role="columnheader" role="cell" to v-calendar with type = “month”

Motivation and Context

fixes #14604

The table content such as "SUN", "MON", "TUE" etc. is presented using <div> elements.
As a result, screen reader users cannot understand the data table content effectively.

How Has This Been Tested?

Markup:

This is the same code as the following link: https://vuetifyjs.com/en/components/calendars/#usage

<template>
  <div>
    <v-sheet
      tile
      height="54"
      class="d-flex"
    >
      <v-btn
        icon
        class="ma-2"
        @click="$refs.calendar.prev()"
      >
        <v-icon>mdi-chevron-left</v-icon>
      </v-btn>
      <v-select
        v-model="type"
        :items="types"
        dense
        outlined
        hide-details
        class="ma-2"
        label="type"
      ></v-select>
      <v-select
        v-model="mode"
        :items="modes"
        dense
        outlined
        hide-details
        label="event-overlap-mode"
        class="ma-2"
      ></v-select>
      <v-select
        v-model="weekday"
        :items="weekdays"
        dense
        outlined
        hide-details
        label="weekdays"
        class="ma-2"
      ></v-select>
      <v-spacer></v-spacer>
      <v-btn
        icon
        class="ma-2"
        @click="$refs.calendar.next()"
      >
        <v-icon>mdi-chevron-right</v-icon>
      </v-btn>
    </v-sheet>
    <v-sheet height="600">
      <v-calendar
        ref="calendar"
        v-model="value"
        :weekdays="weekday"
        :type="type"
        :events="events"
        :event-overlap-mode="mode"
        :event-overlap-threshold="30"
        :event-color="getEventColor"
        @change="getEvents"
      ></v-calendar>
    </v-sheet>
  </div>
</template>

<script>
  export default {
    data: () => ({
      type: 'month',
      types: ['month', 'week', 'day', '4day'],
      mode: 'stack',
      modes: ['stack', 'column'],
      weekday: [0, 1, 2, 3, 4, 5, 6],
      weekdays: [
        { text: 'Sun - Sat', value: [0, 1, 2, 3, 4, 5, 6] },
        { text: 'Mon - Sun', value: [1, 2, 3, 4, 5, 6, 0] },
        { text: 'Mon - Fri', value: [1, 2, 3, 4, 5] },
        { text: 'Mon, Wed, Fri', value: [1, 3, 5] },
      ],
      value: '',
      events: [],
      colors: ['blue', 'indigo', 'deep-purple', 'cyan', 'green', 'orange', 'grey darken-1'],
      names: ['Meeting', 'Holiday', 'PTO', 'Travel', 'Event', 'Birthday', 'Conference', 'Party'],
    }),
    methods: {
      getEvents ({ start, end }) {
        const events = []

        const min = new Date(`${start.date}T00:00:00`)
        const max = new Date(`${end.date}T23:59:59`)
        const days = (max.getTime() - min.getTime()) / 86400000
        const eventCount = this.rnd(days, days + 20)

        for (let i = 0; i < eventCount; i++) {
          const allDay = this.rnd(0, 3) === 0
          const firstTimestamp = this.rnd(min.getTime(), max.getTime())
          const first = new Date(firstTimestamp - (firstTimestamp % 900000))
          const secondTimestamp = this.rnd(2, allDay ? 288 : 8) * 900000
          const second = new Date(first.getTime() + secondTimestamp)

          events.push({
            name: this.names[this.rnd(0, this.names.length - 1)],
            start: first,
            end: second,
            color: this.colors[this.rnd(0, this.colors.length - 1)],
            timed: !allDay,
          })
        }

        this.events = events
      },
      getEventColor (event) {
        return event.color
      },
      rnd (a, b) {
        return Math.floor((b - a + 1) * Math.random()) + a
      },
    },
  }
</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)

[apfrod]

I'm told by an accessibility tester that the table should use 'scope' attribute, as explained in this guide: https://webaim.org/techniques/tables/data

[KaelWD]

@apfrod NVDA seems to understand it just fine without that, it's probably only necessary for row headers.

[apfrod]

@KaelWD as stated, this still fails audit by my accessibility tester.