Add support for uploading OVAs to VMware

[zmrow]

Issue number:
Implements #1605

Description of changes:

It's probably easiest to read through the PR by commit.

pubsys-config: Add VMware support
     
    This adds everything needed to support VMware specific configuration,
    including credentials.

pubsys: Add VMware 'upload-ova' subcommand
    
    This adds the subcommand `upload-ova` to `pubsys`.  This subcommand is
    meant to be used via `cargo make` and allow a user to upload an OVA to
    one or more VMware datacenters, optionally marking the VM as a template.
    Under the hood, it accomplishes this by running `govc` in the SDK
    container via Docker invocation, similar to how `buildsys` accomplishes
    its task.
    
    Like the rest of `pubsys`, it gets much of its configuration from
    `Infra.toml`.  The configuration details all of the values needed to
    communicate with a vSphere instance, and allows for users to specify
    "common" configuration that multiple datacenters share.  Credentials for
    different datacenters can be specified in a file located at
    `~/.config/pubsys/vsphere-credentials.toml`.  Because we use `govc`
    under the hood, at runtime we check for GOVC_* environment variables and
    allow them to override VMware datacenter config in `Infra.toml` or
    `vsphere-credentials.toml`
    
    The subcommand allows a user to override the name of the resulting VM,
    import spec, and specify a subset of datacenters than what's specified
    in config.

Makefile: Add `upload-ova` and `vmware-template` targets
    
    This change adds the ability to upload a built OVA to one or more VMware
    software defined datacenters.  The `vmware-template` target uploads the
    OVA and marks it as a VM template using the import spec.  Multiple
    environment variables allow a user to override the VM name, list of
    datacenters to upload to, and the import spec used to upload.

PUBLISHING: Split relevent AWS/VMware details into their own guides.
    
    This change splits `PUBLISHING.md` into multiple files to account for
    the differences in publishing Bottlerocket on AWS and VMware.  The
    `PUBLISHING-AWS.md` guide covers publishing and granting access to AMIs,
    and details around SSM parameters.  The `PUBLISHING-VMWARE.md` guide
    covers the configuration details and process for uploading an OVA to one
    or more VMware SDDC's.  The main `PUBLISHING.md` still covers all
    general information around configuration, repos, etc.

Testing done:

I performed the test steps with varying configuration setups:

• only environment variables (no datacenter-specific details in Infra.toml or creds file)
• only datacenter config/credentials file (no environment variables)
• datacenter config/creds file with values missing but populated in the environment
• environment variables with values missing but populated in the files
• all config populated in the [vmware.common] section
• various values populated in common, Infra.toml and environment to ensure the values cascade as expected

Testing steps:

• Upload an OVA
• Upload an OVA as template
• Override VM name, import_spec, and datacenters. (I don't have multiple datacenters to push to so I populated the same details for multiple datacenters and ensured that pubsys attempts to upload to them both, failing the second time because a VM already exists)
• Attempt to re-upload the same OVA, fails as expected with a nice message:

[INFO] Uploading OVA to datacenter 'main' with name 'bottlerocket-vmware-k8s-1.20-x86_64-v1.1.1-5bf37a18-dirty'                                                                      
Failed to upload OVA: Docker invocation failed: /usr/bin/govc: The name 'bottlerocket-vmware-k8s-1.20-x86_64-v1.1.1-5bf37a18-dirty' already exists

Terms of contribution:

By submitting this pull request, I agree that this contribution is dual-licensed under the terms of both the Apache License, version 2.0, and the MIT license.

[webern]

saving partial review

[zmrow]

^ addresses @webern 's comments!

[zmrow]

^ Removes the TryFrom implementation in favor of a build() method on the *Builder structs.

[zmrow]

^ Above push is a rebase on develop.

Now the the SDK changes are shipped, I executed all of the testing again and everything looks good. (Fighting through the intermittent VMC issues today)

Pulling out of draft...

[arnaldo2792]

Nit:

Suggested change

	return Ok(output);
	Ok(output)

[zmrow]

^ Addresses @arnaldo2792 's comments :)

[arnaldo2792]

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