feat(VDatePicker): add header-color props

[SonTT19]

Description

resolves #18310

Markup:

<template>
  <v-app theme="light">
    <v-container>
      <v-row justify="space-around">
        <v-date-picker
          color="primary"
        ></v-date-picker>

        <v-date-picker
          color="primary"
          header-color="secondary"
        ></v-date-picker>
      </v-row>
    </v-container>
  </v-app>
</template>