feat(VCombobox): always show only matching suggestions

[jcjp]

Description

closes #22060
Relates to: #21901

• Add new props alwaysFilter defaults to false to allow the previous behavior consistent with components like VSelect and VAutocomplete
• If set to true it will prevent to set the isPristine to false on initial load
• Instead of passing the search immediately check isPristine and determine the value to pass

Markup:

// This example will show the previous behavior
// On menu show it should show all the items
// Pass always-filter to see it filter on load
<template>
  <v-app>
    <v-container>
      <v-combobox
        v-model="msg"
        :items="['Colorado', 'Florida', 'Georgia', 'Texas', 'Wyoming', 'California']"
      />
    </v-container>
  </v-app>
</template>

<script setup>
  import { ref } from 'vue'

  const msg = ref('Cali')
</script>

[J-Sek]

Menu gets unstable (opens, closes, opens, etc.) again after typing few more characters with no match.

I deliberately removed isPristine from useFilter(...) to have filterdItems predictable and depending only on the search and _searchLock (to be introduced in one of the outstanding PRs). I don't mind having it back if we can avoid regression... just feeling like we made a wrong turn at some point and state/behavior is very hard to track and impossible to keep the bugs out.

I think this looks good, added 1 test case scenario ready for round of review thanks!

[J-Sek]

Looks good 👍🏼
We need an entry in new-in.json and a description for API docs that would include "matching", "suggestions" keywords and a hint about :menu-icon="false" and hide-selected for optimal UX.

All done let me know if it's correct Jacek thanks!

[J-Sek]

In my opinion it is more of a fix than a feature. We just deliver it using a separate prop to avoid unexpected behavior change in all the use cases where it is expected to act like an enhanced VAutocomplete.