Redirect PluginWrapper root URL to third-party licenses view

[somiljain2006]

Fixes ~#16812

Redirect requests to the PluginWrapper root URL (/plugin//wrapper/) to the thirdPartyLicenses view. This fixes a 404 error encountered when clicking the plugin name on the "License and dependency information" page.

Testing done

Ensured all tests still passed.

Screenshots (UI changes only)

Proposed changelog entries

Fix a 404 error when clicking plugin names on the “License and dependency information for plugins” page.

Proposed changelog category

/label bug

Proposed upgrade guidelines

N/A

Before the changes are marked as ready-for-merge:

Maintainer checklist

• There are at least two (2) approvals for the pull request and no outstanding requests for change.
• Conversations in the pull request are over, or it is explicit that a reviewer is not blocking the change.
• Changelog entries in the pull request title and/or Proposed changelog entries are accurate, human-readable, and in the imperative mood.
• Proper changelog labels are set so that the changelog can be generated automatically.
• If the change needs additional upgrade steps from users, the upgrade-guide-needed label is set, and there is a Proposed upgrade guidelines section in the pull request title (see example).
• If it would make sense to backport the change to LTS, be a Bug or Improvement, and either the issue or pull request must be labeled as lts-candidate to be considered.