Fix 19798 tweaks

[J-Sek]

PR consists of 2 independent parts:

• refactoring to make it clear none of the update:model-value emits from VTextField are accepted (because all of them provide type string, they were already filtered out by the _model wrapper)
• test cases (mostly failing) to guide further implementation tweaks
  • scenarios for mixed usage of typing (adding/removing digits) and incrementing value (up/down arrows)
  • additional scenarios to ensure consistent state after blur

There is one more advanced scenario that works around auto-cleanup on blur (initial typing for -0.21 is actually optional)

1. focus input with existing value and change text without changing effective number
   • e.g. -.21, -0000.21, -0.2100
2. after blur the text stays the same
   • it might not be a critical bug, but it is inconsistent with behavior when we type a new value, developers might be bothered by their QA team about this

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Supports #20211

[yuwu9145]

As it has been mentioned before, this change breaks external v-model value enforcement

In this example, expected behaviour should be input value fall back to min 5

<template>
  <v-app>
    <v-container>
      <h1>{{ typeof typed }}</h1>
      <h1>{{ typed  }}</h1>
      <v-number-input
        label=""
        clearable 
        v-model="typed"
        :hideInput="false"
        :inset="false"
        :min="5"
        :max="125"
        :step="0.32"
      ></v-number-input>
    </v-container>
  </v-app>
</template>

<script setup>
  import { ref } from 'vue'
  const typed = ref(-5)
</script>

[J-Sek]

@yuwu9145 It does, you are right... weird I missed it. My focus was on the behavior of unrestricted field.

• shouldn't we have some test cases for it?
• wouldn't it be more clear to put clam in onBlur to enforce it rather than relying on some magic side-effect of @update:model-value?

Edit: It seems that missing @update:model-value makes it possible for model to become out-of-sync with VTextField, hence onBlur fixes nothing.