Remove metal-* UI components dependencies

[jbalsas]

It has been decided to reduce the metal.js surface to only core+plugins as it was always intended.

For that reason, we have already started deprecating and archiving all the ui-related metal components. We should remove all dependencies in this project like metal-dropdown and keep our own versions as they will no longer be available in the future.

[jbalsas]

Don't we have any other dependency other than metal-dropdown?

[matuzalemsteles]

Hey @jbalsas, Yes, we only had metal-dropdown as a dependency. 🙂

[jbalsas]

Awesome! 👏