use dinamically downloaded charts instead of a Git submodule
Also refactored validation to take advantage of Gin's built-in features.
Bug: T361516
How to register an account on GitLab. To prevent spam, new accounts are locked until approved by an admin or the approver bot. You can also file an unlock request to expedite access.
Support: mw:GitLab, how to host a project on GitLab, #wikimedia-gitlab on libera.chat, #GitLab on Phabricator.
Also refactored validation to take advantage of Gin's built-in features.
Bug: T361516