Some refactoring on how provider metadata is handled

[rsjostrand-hpe]

Summary and Scope

Performed some refactoring with how ProviderMetadata is handled.

• There is a top level structure in the CSM package called Metadata that is composed of the Node and Cabinet structures.
  • Removed CSM hardware structure as it basically became csm.Metadata
• Renamed ProviderProperties to ProviderMetadata to align naming.
• Created enums for all supported provider metadata keys.
• There is always nil or map[string]interface{} in provider metadata. There are no structs ever
  • Added DecodeProviderMetadata and EncodeProviderMetadata to csm package. GetProviderMetadata and GetProviderMetadataT were removed.
  • Calls to mapstructure in the cmd package were replaced with csm.DecodeProviderMetadata.-
• inventory.Hardware changes
  • Removed top level fields Role/SubRole/Alias from the inventory.Hardware structure, as they are duplicated with the provider metadata.
  • Added SetProviderMetadata method to inventory.Hardware
  • Change type of ProviderProperties/ProviderMetadata to map[Provider]ProviderMetadataRaw to force the type usage for this field.
• Created pointers package to help with dealing with pointer values.

Heavily relying on the automated testing provided by make test to verify things are ok after the refractor.

Here is what a cabinet looks like in the canidb. Notice how Provider metadata is under a different key, and that the Cabinet properties are namespaced under CSM:

{
  "ID": "fcbf7a07-c0a1-4f0c-a0ba-b126a1d78786",
  "Type": "Cabinet",
  "DeviceTypeSlug": "hpe-ex2000",
  "Vendor": "HPE",
  "Model": "EX2000",
  "Status": "staged",
  "ProviderMetadata": {
    "csm": {
      "Cabinet": {
        "HMNVlan": 3006
      }
    }
  },
  "Parent": "abcdef12-3456-2789-abcd-ef1234567890",
  "Children": [
    "40b53fec-bcb2-4b9c-b18c-3b4db7862bfa",
    "72dbfa6d-9b92-43bd-b2e2-d7eb4f70d1a8",
    "e278bbb6-2cab-4ba4-a91d-3a402c83f924"
  ],
  "LocationPath": [
    {
      "HardwareType": "System",
      "Ordinal": 0
    },
    {
      "HardwareType": "Cabinet",
      "Ordinal": 9006
    }
  ],
  "LocationOrdinal": 9006
}

Risks and Mitigations

[jacobsalmela]

Very cool. I like how it reduces the Hardware type, too. Nice work!