Store allowlist of third-party plugins in a JSON file

From @edsummersnc:

> Consider refactoring the list of approved plugins into a JSON file or similar file type. Include npm package name, description, and repo. This will allow users of the scanner to find third-party plugins, perform their own security review, file issues on those plugins, contribute fixes, fork/extend, etc.

The allowlist is currently maintained in the repo's codebase, as it contains only a single entry.

Locate the current approved-plugin allowlist in the repository codebase and read how it is consumed. Move the list into a JSON file containing each npm package name, description, and repository, then verify the scanner still discovers the existing plugin from that file.

Vom Indexierungsmodell aus dem Issue-Text verfasst.