[sc-323687] Feat: Add Cobuild support metadata

[alexandremgo]

Overview

Card: sc-323687

• Marks the send-mails-from-contacts-dataset recipe as Cobuild-supported.
• Adds concise component guidance for configuring sender, subject, body, DSS mail channels, and direct SMTP.
• Keeps the existing descriptor requiredness unchanged (to avoid breaking changes) while documenting runtime requirements that it does not express:
  • output must reference an existing dataset because the runner dereferences it and writes per-row delivery status.
  • Direct SMTP authentication requires both smtp_user and smtp_pass; password entry is handed off to the DSS recipe settings.
• Documents cross-field requirements that the descriptor cannot express individually: sender, subject, and body must each come from the appropriate column or configured value, unless the selected channel supplies the sender.
• Guides Cobuild to discover usable DSS mail channels, ask the user when several are available, and use the plugin's canonical values for channel-defined senders and direct SMTP.

Cobuild plugin-recipe support is implemented by dataiku/dip#49952.

[duynghiatran]

I think we need to bump the version