Add support for local file URLs and CDN URIs in LinkIt plugin.

Problem/Motivation

The Acquia DAM Linkit substitution plugin doesn't handle different asset download configurations. The plugin currently assumes all DAM assets should use the acquia-dam:// URI scheme, but when the DAM source is configured to download assets locally, it should generate URLs to the local file instead.

Steps to reproduce

• Create linkit plugin
• Add media matcher with DAM media types
• Add linkit plugin to CKEditor with Media entity URL substitution "Direct URL to Acquia DAM Assets"
• Update any media type to use Download and Sync rendering method
• Add content and link DAM media
• Visit content, assets URL is CDN URL and not Local URL

Proposed resolution

• Add logic to check the DAM source's download_assets configuration
• When download is enabled, generate URLs from the local file entity
• When download is disabled, maintain the existing acquia-dam:// URI behavior
• Ensure backward compatibility with existing configurations