WIP: Add OSSF Scorecard workflow to repository-base

[erikgb]

This adds a slightly modified version of https://github.com/cert-manager/cert-manager/blob/6c9253775a067378b6d237982fab105601611901/.github/workflows/scorecards.yml to the repository-base module. This should ensure we get code scanning in all projects using makefile-modules.

Compared with the original, I have modified the following:

• Added a generated note header
• Removed the cron schedule, as pushes to the default branch probably will happen often enough
• Extended the push clause with both our variants of default branch name: main and master
• Changed file extension from .yml to .yaml (this will require a manual upgrde in cert-manager)

[cert-manager-prow]

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[erikgb]

/cc @inteon