[Issue] Developer Experience: Make getAdditionalConfig extensible

[m2-assistant]

This issue is automatically created based on existing pull request: #30718: Developer Experience: Make getAdditionalConfig extensible

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Description (*)

For 2.5 branch

Currently when you need to add some extra data to Configurable Swatches, you need either:

• Inherit class and add your custom elements
• Plugin end decode the data before adding your

Example from Extension Vendor code:

To avoid such situations, I introduced the change that enables us to put our own data in Swatch config without unnecessary hassle.

Related Pull Requests

Fixed Issues (if relevant)

1. Fixes magento/magento2#<issue_number>

Manual testing scenarios (*)

1. ...
2. ...

Questions or comments

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds are green)