feat: Backstage plugin supports static token

[mdb]

This addresses issue #20382 and gives users of the Backstage Raycast plugin the ability to authenticate to Backstage via a static token.

Checklist

• I read the extension guidelines
• I read the documentation about publishing
• I ran npm run build and tested this distribution build in Raycast
• I checked that files in the assets folder are used by the extension itself
• I checked that assets used in the README are located outside the metadata folder if they were not generated with our metadata tool