Add "Type" field to asset links on "Edit Release" page

What does this MR do?

Adds a new Type dropdown to the assets links portion of the Edit Release page.

Feature flag

This dropdown will only be shown if the release_asset_link_type feature flag is enabled. By default, this feature flag is disabled.

However, the frontend does send the type field when interacting with the API server regardless of this feature flag. I didn't bother hiding this field as the API server ignores properties that it doesn't know about, so this is safe to merge before the backend is completed.

Screenshots

List of options

Mobile view

First step towards #207257 (closed)