bug: wrong evaluation when there are multiple tags set for artifact_signature

[rdimitrov]

Describe the bug

The policy status is incorrect when we set more than 1 tag in a policy using the artifact_signature rule.

To Reproduce

Steps to reproduce the behavior:

1. Start Mediator
2. Register it to a repository producing signed artifacts
3. Set and create a policy using the artifact_signature rule configured with more than 1 tag, i.e. tags: [main, latest]
4. Build, publish, sign the image from the registry with just a single tag, i.e. main only
5. Evaluate the policy status

Expected behavior

In the case above it should have failed, instead it passed.

Part of the fix is to update the way we compare the tags in https://github.com/stacklok/mediator/blob/f362a4632e176613c89bc01219d8464e42f01bd4/internal/engine/ingester/artifact/artifact.go#L113 to HasAll.

Another use case that it failed (with the up-mentioned change) is:

• build an image with the correct set of tags, i.e. [main,prod,latest]
• have a policy configured to check for [main,prod]
• evaluating it passes and it's okay
• then we build and push and sign a new image containing only one of the tags, i.e. main
• evaluating the same policy still shows as successful when it shouldn't have (main tag is now tailored to another image)

Screenshots
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Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context
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[rdimitrov]

Related to #831