Introduce Allstar to enforce branch protection on repositories

[dlabordus]

The GitHub Application 'Allstar' was recommended to be used.
It can enforce different thinks, see https://github.com/ossf/allstar.

The most useful one for now look to be 'Branch Protection'.
And we should also look at the 'Binary Artifacts' to create a Score Card.

Remark: They mostly talk about creating a repository '.allstar' to enforce it on organization level.
But the existing repository '.github' can also be used (in the directory "allstar" the same files can be added).

[Sander3003]

@nicorikken is it useful to use this? What is your opinion?

[Flurb]

@nicorikken is it useful to use this? What is your opinion?

Yes, the Branch Protection option is definitely useful for us!