* add SignContent() + integrate into configAPI
* use static client for upload versions tool; fix staticupload calleeReference bug
* use version to get proper cosign pub key.
* mock fetcher in CLI tests
* only provide config.New constructor with fetcher
Co-authored-by: Otto Bittner <cobittner@posteo.net>
Co-authored-by: Daniel Weiße <66256922+daniel-weisse@users.noreply.github.com>