feat: provide support for .conf-only add-ons

[hetangmodi-crest]

Issue number: ADDON-76820

PR Type

What kind of change does this PR introduce?

• Feature
• Bug Fix
• Refactoring (no functional or API changes)
• Documentation Update
• Maintenance (dependency updates, CI, etc.)

Summary

Changes

We have extended our support for conf-only-TA's. Files that will be generated for conf-only-TA are :

• app.conf
• globalConfig.json
• openapi.json
• metadata/default.meta
• README.txt
• VERSION

User experience

Users can now use ucc-gen build command for their conf-only-TA's.

Checklist

If an item doesn't apply to your changes, leave it unchecked.

• I have performed a self-review of this change according to the development guidelines
• Tests have been added/modified to cover the changes (testing doc)
• Changes are documented
• PR title and description follows the contributing principles