feat(VDatePicker): Calculate disabled year and month

[ikushum]

fixes #20465

Description

Disable month and year buttons based on allowed-dates prop when:

• allowed-dates is array (done in feat(VDatePicker): disable months and years if not allowed #21466)
• allowed-dates is function

‼️ This is a follow up PR for #21466 and completes the second checkbox from list above. The changes in this PR are slightly computation heavy so wanted to have some discussion and see if the code is worth it.

If the allowed-dates prop is function then:

• Code inside allowedYears will execute approx 366 * 150 = 54900 times
• Code inside allowedMonths will execute approx 31 * 12 = 372 times

Markup:

<template>
  <v-app>
    <v-container>
        <h2>Date picker</h2>
        <v-date-picker
          mode="month"
          hide-header
          :allowed-dates="allowedDates"
        ></v-date-picker>

        <h2>Date picker years</h2>
        <VDatePickerYears
          :allowed-years="[2025, 2026]"
          class="mb-10"
        />

        <h2>Date picker months</h2>
        <VDatePickerMonths
          :allowed-months="[2, 3]"
        />
    </v-container>
  </v-app>
</template>

<script setup>
const allowedDates = value => value > new Date()
</script>

[J-Sek]

Yup. Worst case scenario is ~55k roundtrips, but also it takes < 300ms (with console log commented out), so it basically depends on complexity of that function... in addition to the devs being careless by forgetting to put min and max

<template>
  <h2>Select winter holiday with the most epic party</h2>
  <v-date-picker :allowed-dates="allowedDates" mode="month" hide-header />
</template>

<script setup lang="ts">
  const allowedDates = (v: Date) => {
    // console.count('allowedDates') // over 54500
    return v.getMonth() === 11 && v.getDate() > 21
  }
</script>