Bring core entities pipeline to matrix repository

[JacquesVergine]

Description of the changes

This PR brings the core-entities code in this repository. You can find more information about it in its own README.

These are the adaptation I had to do to bring this to matrix:

• Add the Google sheet service account path (gsheet_service_account.json) in actions
• Move Github secrets for actions
• Update copy/pasted matrix datasets to now be imports: move GitHubReleaseCSVDataset and add GBQTableDataset to matrix-gcp-datasets lib

Out of scope:

• Update test/01_raw files to use the fabricator

Checklist:

• Added label to PR (e.g. enhancement or bug)
• Ensured the PR is named descriptively. FYI: This name is used as part of our changelog & release notes.
• Looked at the diff on github to make sure no unwanted files have been committed.
• Made corresponding changes to the documentation
• Added tests that prove my fix is effective or that my feature works
• Any dependent changes have been merged and published in downstream modules
• If breaking changes occur or you need everyone to run a command locally after
  pulling in latest main, uncomment the below "Merge Notification" section and
  describe steps necessary for people
• Ran on sample data using kedro run -e sample -p test_sample (see sample environment guide)