feat(pyproject): Add PDM Dockerize `tool.pdm.dockerize` schema

[noirbizarre]

Hello,

This PR add supports for the PDM Dockerize extension which is using the tool.pdm.dockerize table in pyproject.toml. As it is an extension, I chose to submit the schema as an extra partial-pdm-dockerize.json schema instead of having it inlined in partial-pdm.json

[github-actions[bot]]

Thanks for the PR!

This section of the codebase is owned by @madskristensen and @hyperupcall - if they write a comment saying "LGTM" then it will be merged.

[madskristensen]

Thanks