ci: Add GH action to check for TSC votes on core dataset changes

[merelcht]

Description

Add an automated check to get 1/2 TSC approvals on core dataset changes.

Development notes

This solution isn't perfect, because it will also trigger on any changes to existing datasets and we only need an official votes for new datasets being contributed to the core datasets.

I suggest we don't make this a mandatory check, but it will serve as an automatic reminder to check if we need a TSC vote.

Example of this check in action: https://github.com/merelcht/kedro-plugins/pull/3

Checklist

• [ ] Opened this PR as a 'Draft Pull Request' if it is work-in-progress
• [ ] Updated the documentation to reflect the code changes
• [ ] Added a description of this change in the relevant RELEASE.md file
• [ ] Added tests to cover my changes
• [ ] Received approvals from at least half of the TSC (required for adding a new, non-experimental dataset)

[ankatiyar]

This will need to be added to the merge-gatekeeper.yml under ignored tests so it doesn't block the merging on other PRs