Fix #2989: dcc.Dropdown options order preserved during search

[ines-om]

This PR fixes #2989.

When searching in dcc.Dropdown, search results should be presented in the original option order instead of being reordered by js-search. This is achieved by creating a Set of the search results and filtering the original options array against it, preserving the intended order.

Contributor Checklist

• I have broken down my PR scope into the following TODO tasks
  • Implement Set-based filtering in DropdownSearch.tsx to preserve user-defined order in search results
  • Add tests for various option ordering scenarios, including ordering in multi-value dropdowns
• I have run the tests locally and they passed. (refer to testing section in contributing)
• I have added tests, or extended existing tests, to cover any new features or bugs fixed in this PR

optionals

• I have added entry in the CHANGELOG.md
• If this PR needs a follow-up in dash docs, community thread, I have mentioned the relevant URLS as follows
  • this GitHub #PR number updates the dash docs
  • here is the show and tell thread in Plotly Dash community