Support image signing

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#### Description

Would it be possible to integrate image signing?

For example, cosign allows signing of containers and binaries (respectively generic artifacts).

#### Use Case(s)

Some projects only offer amd64 images because they don't have arm64 hardware.
And vice versa, Apple Silicon MacBooks can't build amd64 images.

If signing would be integrated, two developers could contribute their own architecture to the same project while still being able to prove authenticity at the same time.

#### Potential configuration

cosign is directly usable as a Go dependency.
https://pkg.go.dev/github.com/sigstore/cosign/v2

#### Potential References

https://github.com/sigstore/cosign#working-with-other-artifacts