Add Provider VDC and VM Group data sources, VM Placement policies resource+data source and support for VM Placement policies in VDCs

[adambarreiro]

This PR solves issue #898.
This PR requires vmware/go-vcloud-director#502 and vmware/go-vcloud-director#504.

Context

The goal is to solve #898. To achieve that, we need to handle references to VM Placement Policies in a new attribute vm_placement_policy_ids in the VDC resources and data sources. As we don't have that mechanism, we need a new data source to fetch them: vcd_vm_placement_policy. At same time, to fetch these VM Placement Policies we need a reference to its associated Provider VDC, as one can have same name VM Placement Policies belonging to different Provider VDCs, hence a new data source vcd_provider_vdc is also required.

For the sake of automating the testing of all of these, the vcd_vm_placement_policy resource has been implemented as well. To create them we also need the vcd_vm_group data source which is also created in this PR.

That's why this PR adds so many things (the three mentioned data sources + new resource + new attribute in VDC), as they are part of the same story.

Features and improvements

• vcd_org_vdc deprecates default_vm_sizing_policy_id because the name is incorrect, as this attribute is currently holding Sizing Policies, Placement Policies or vGPU Policies. A new attribute default_compute_policy_id has been added to replace it, which represents a more accurate behaviour (A Compute Policy is a superset of the three types mentioned).

  The idea is also that the logic considers default_vm_sizing_policy_id as a fallback of default_compute_policy_id if the latter is not populated. This can be done as they hold the same value (in the end is just the name which is incorrect).

• vcd_org_vdc has a new attribute vm_placement_policy_ids to support VM Placement policies of the corresponding VDC.

• New data source vcd_vm_placement_policy to fetch VM Placement Policies given a name and a Provider VDC URN.

• New resource vcd_vm_placement_policy to create VM Placement Policies given a name, a Provider VDC URN and a set of VM groups or Logical VM Groups.

• As previous data source requires a Provider VDC URN, a vcd_provider_vdc data source has been added to fetch this. Now pVDCs can be obtained with a name.

• New data source vcd_vm_group to fetch VM Groups to be used to create VM Placement Policies.

Minor refactors

• Moved ifIdIsPartOfSlice(id string, ids []string) bool from resource_vcd_org_vdc.go to structure.go as it is an generic/utility function, changed its name and signature to contains(sliceToSearch []string, searched string) bool which is more readable.
• Tried to improve a bit the readability of vcd_org_vdc part that handles Compute Policies and reduce duplicated code, with not much luck.

Testing

Tests require a new field in vcd_test_config.json:

"vcd": {
    ...
    "nsxtProviderVdc": {
        ...
        "placementPolicyVmGroup": "testVmGroup",
    }
}

• Manual playing done for vcd_vm_group data source.
• Manual playing done for vcd_provider_vdc data source.
• Manual playing done for vcd_vm_placement_policy resource and data source.
• Manual playing done for vcd_org_vdc with VM Sizing Policies, VM Placement policies and playing with the default Compute Policy
• Acc tests pass in VCD 10.3
• Acc tests pass in VCD 10.4

[dataclouder]

Some small changes needed