Clean up license norming diagnostic output

[chennes]

It was impossible to tell which addons had unrecognized or un-normalizable licenses before: this modifies the diagnostic output so it's clear which addons have non-SPDX license identifiers.

[Copilot]

Pull Request Overview

This PR improves diagnostic output for license normalization by making it clear which addons have unrecognized or non-normalizable license identifiers. The changes modify the license normalization process to provide informative output about license validation failures and successful normalizations.

Key changes:

• Modified license normalization to return None for unrecognizable licenses instead of the original string
• Added diagnostic output to identify which addons have problematic license identifiers
• Updated callers to handle the new return type and provide meaningful feedback

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
addonmanager_licenses.py	Changed normalize method to return Optional[str] and removed internal logging
addonmanager_metadata.py	Added diagnostic output for license normalization issues with addon names
addonmanager_macro_parser.py	Added warning/info messages for license normalization failures and successes

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}