[storewolf] Improve default metadata representation

[zmrow]

This commit improves how metadata is represented in our defaults.toml.
Previously each metadata entry required a seperate 4 line declaration,
which is noisy and unpleasant. With this change, metadata for each
corresponding setting can be defined together in a single metadata
entry.

The commit adds a single function to translate this new defaults toml
format into a Vec which is processed in storewolf exactly
the same as we did previously.

*Please closely double check my edits of defaults.toml!

Issue #, if available:
Fixes #135

Description of changes:

• Update defaults.toml to new format
• Add function to parse new defaults.toml metadata format and convert to Vec

Testing done

• Datastore on an image created with this PR has identical structure with a prior Thar image.
• On my dev box I'm able to create a datastore that looks correct

[mrowicki@ip-10-0-60-75 api]$ ../target/debug/storewolf --data-store-base-path /tmp/mrowicki --version 1.0
20:03:09 [ INFO] Storewolf started
20:03:09 [ INFO] Deleting pending settings
20:03:09 [ INFO] Populating datastore at: /tmp/mrowicki
20:03:09 [ INFO] Creating datastore at: /tmp/mrowicki/current/live
20:03:09 [ INFO] Datastore populated

[mrowicki@ip-10-0-60-75 api]$ tree /tmp/mrowicki/
/tmp/mrowicki/
├── current -> v1
├── v1 -> v1.0
├── v1.0 -> v1.0_NLEMxi3UTTT7U6nH
└── v1.0_NLEMxi3UTTT7U6nH
    ├── live
    │   ├── configuration-files
    │   │   ├── chrony-conf
    │   │   │   ├── path
    │   │   │   └── template-path
    │   │   ├── containerd-config-toml
    │   │   │   ├── path
    │   │   │   └── template-path
    │   │   ├── hostname
    │   │   │   ├── path
    │   │   │   └── template-path
    │   │   ├── kubelet-config
    │   │   │   ├── path
    │   │   │   └── template-path
    │   │   ├── kubelet-env
    │   │   │   ├── path
    │   │   │   └── template-path
    │   │   ├── kubelet-kubeconfig
    │   │   │   ├── path
    │   │   │   └── template-path
    │   │   ├── kubernetes-ca-crt
    │   │   │   ├── path
    │   │   │   └── template-path
    │   │   └── updog-toml
    │   │       ├── path
    │   │       └── template-path
    │   ├── services
    │   │   ├── host-containers
    │   │   │   ├── configuration-files
    │   │   │   └── restart-commands
    │   │   ├── hostname
    │   │   │   ├── configuration-files
    │   │   │   └── restart-commands
    │   │   ├── kubernetes
    │   │   │   ├── configuration-files
    │   │   │   └── restart-commands
    │   │   ├── ntp
    │   │   │   ├── configuration-files
    │   │   │   └── restart-commands
    │   │   └── updog
    │   │       ├── configuration-files
    │   │       └── restart-commands
    │   └── settings
    │       ├── host-containers.affected-services
    │       ├── hostname.affected-services
    │       ├── kubernetes
    │       │   ├── cluster-dns-ip.setting-generator
    │       │   ├── max-pods.setting-generator
    │       │   ├── node-ip.setting-generator
    │       │   └── pod-infra-container-image.setting-generator
    │       ├── kubernetes.affected-services
    │       ├── ntp.affected-services
    │       ├── updates
    │       │   └── seed.setting-generator
    │       └── updates.affected-services
    └── pending
        └── settings
            ├── host-containers
            │   ├── admin
            │   │   ├── enabled
            │   │   ├── source
            │   │   └── superpowered
            │   └── control
            │       ├── enabled
            │       ├── source
            │       └── superpowered
            ├── hostname
            ├── ntp
            │   └── time-servers
            ├── timezone
            └── updates
                ├── metadata-base-url
                └── target-base-url

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[tjkirch]

I think this error message just duplicates what's going to be in the source error; it might be better to give a pointer to the input that unexpectedly contained a newline. The path?

[etungsten]

🌲

[zmrow]

Addressed comments from @tjkirch

[zmrow]

Fixed error text per @tjkirch !

[zmrow]

Oh - and rebased as well. :)

[tjkirch]

Approval stands!