feat(VNumberInput): support append/prepend inner slots/icons

[yuwu9145]

Description

Add proper support of append/prepend inner slots/icons in VNumberInput

fixes #20782

Markup:

<template>
  <v-app>
    <v-container>
      <v-number-input prepend-inner-icon="mdi-alert" reverse />
      <v-number-input prepend-inner-icon="mdi-square" hide-input />
      <v-number-input hide-input />
      <v-number-input prepend-inner-icon="mdi-circle-outline" />
      <v-select prepend-inner-icon="mdi-check" placeholder="Normal padding" />
    </v-container>
  </v-app>
</template>

<style>
  /*
  uncomment to revert to default v-field-preppended padding


  .v-field.v-field--prepended {
    padding-inline-start: 12px;
  }

  */
</style>