Ensure plugin can also work as a local plugin for poetry > 2

[ag14774]

poetry-monoranger-plugin cannot work as a local/project plugin at the root repo.

It has to be installed globally. Alternatively, it can be added as a project plugin to each of the sub-projects. There is no way around this because the plugin needs to be loaded somehow before it can start patching the various internal method for install, lock, etc. Since poetry only looks at the plugins in the current sub-package, it will never load the plugin from the parent/root project.

More #80, #86

To consider this resolved:

• When installing as a sub-package local plugin, the first time it is installed, a lockfile is created. After the lockfile is deleted, subsequent poetry install work fine
• Investigate whether we can have an additional feature that loads plugins from the monorepo root (except poetry-monoranger-plugin itself)
• Improve docs on this issue