fix(signing): Document or remove insecureAcceptAnything sources in policy.json

[RoyalOughtness]

           "": [
                {
                    "type": "insecureAcceptAnything"
                }
            ]
        },
        "docker-daemon": {
            "": [
                {
                    "type": "insecureAcceptAnything"
                }
            ]
        },
        "atomic": {
            "": [
                {
                    "type": "insecureAcceptAnything"
                }
            ]
        },
        "containers-storage": {
            "": [
                {
                    "type": "insecureAcceptAnything"
                }
            ]
        },
        "dir": {
            "": [
                {
                    "type": "insecureAcceptAnything"
                }
            ]
        },
        "oci": {
            "": [
                {
                    "type": "insecureAcceptAnything"
                }
            ]
        },
        "oci-archive": {
            "": [
                {
                    "type": "insecureAcceptAnything"
                }
            ]
        },
        "docker-archive": {
            "": [
                {
                    "type": "insecureAcceptAnything"
                }
            ]
        },
        "tarball": {
            "": [
                {
                    "type": "insecureAcceptAnything"
                }
            ]
        }

It's not clear what purpose these serve if any. If they do serve a purpose, they should be documented. If they don't, they should be removed.

[xynydev]

I am almost certain that those are there, because something was broken if they aren't. However, I am no expert on policy.json, so @gerblesh should take a look at this.

[gerblesh]

mainly comes from upstream uBlue to not break compatibility with unsigned images or images that can't be verified, it has led to some unwanted behavior when leaving a lot of it to "reject" from users, which is why presumably it has been configured this way. While this definitely isn't the best, I don't want to change anything in fear of breaking someone's containers. I'd take this up with upstream uBlue and ask around.