Plugin-add doesn't work for Gitlab registries

[Xilonz]

The plugin-add command doesn't work for Gitlab registries.
The required metadata { lando: {} } or { keywords: ['lando-plugin']] are not exposed through the api.

Example Gitlab NPM metadata for the package:

{"name":"@arjan/lando-hostfile","versions":{"0.0.1":{"dist":{"shasum":"ebcfcd755ecbba3958541f477b80dbf6db1b348d","tarball":"https://my-personal-gitlab.nl/api/v4/projects/355/packages/npm/@arjan/lando-hostfile/-/@arjan/lando-hostfile-0.0.1.tgz"},"name":"@arjan/lando-hostfile","version":"0.0.1","dependencies":{"lodash":"^4.17.20"}}},"dist-tags":{"latest":"0.0.1"}}

Proposed solution:
Add an argument to --force the installation, skipping the validation.
Since Gitlab is planning to add full meta support, I don't think any additional changes are needed.

GitLab's tracking issue for full metadata support:
https://gitlab.com/gitlab-org/gitlab/-/issues/344107