Backport of #10397 to core/1.42
**⚠️ Significant conflict resolution:** This PR migrates SingleSelect
and MultiSelect from PrimeVue to Reka UI components. All conflicts were
resolved by accepting the incoming (PR) version. The select.variants.ts
and test files are new additions.
Resolved conflicts:
- MultiSelect.vue: 6 content conflicts (accept incoming Reka UI version)
- SingleSelect.vue: 2 content conflicts (accept incoming Reka UI
version)
- MultiSelect.test.ts: modify/delete (kept new test file)
Co-authored-by: Jin Yi <jin12cc@gmail.com>
