Add command to view cluster manifests

[xenowits]

🎯 Problem to be solved

The cluster manifest files are in binary (protobuf) format so is not human readable. But often times, we want to check the contents of a cluster manifest. For example, we may want to check if the manifest contains our new validators after running the add-validators-solo command.

We should provide a way for our users to easily check contents of a cluster manifest file.

🛠️ Proposed solution

Add a new command charon alpha view-cluster-manifest which:

• loads a manifest file from path specified by the --manifest-file flag
• reads the cluster data from the file
• prints the cluster data in a human-readable format (json)

Note that we can probably use the protojson package for this.

🧪 Tests

• Tested by new automated unit/integration/smoke tests
• Manually tested on core team/canary/test clusters
• Manually tested on local compose simnet