[Custom templates] Dropdown component: Update with search capabilities and progressive disclosure

### Description
Enable a search field in dropdown menus to expose search capabilites and improve usability.

### Why it matters
Not having a search field makes it difficult to use the dropdown menus with large lists. It reduces efficiency, impedes discoverability and accessibility for keyboard and screen reader users.

### Videos

#### Azure portal dropdown experience.
Ideal experience.

https://github.com/user-attachments/assets/2a21c4e6-4ed9-4cb1-ba6e-bcee4ccb7a09

#### Logic Apps Templates: Create experience:
This experience kinda provides a 'search field' experience, but the large menu layout that takes over the screen overwhelms users with an excessive interface for a simple task.

https://github.com/user-attachments/assets/35825789-5ea2-488c-aa99-121e98c422b2

#### Logic Apps Templates: Choose workflow experience
A lot of friction. Requires a lot of scrolling. Difficult to complete task. Not sure our keyboard and screen reader community will be able to use this because screen readers must read every item aloud as users move through them, which is inefficient and increases cognitive fatigue.

https://github.com/user-attachments/assets/db0509dc-8298-4de4-8a2d-4ae13524fcfd