Use HCP Consul and HCP Vault for the Consul and Vault clusters used in E2E testing. This has the following benefits:
* Without the need to support mTLS bootstrapping for Consul and Vault, we can simplify the mTLS configuration by leaning on Terraform instead of janky bash shell scripting.
* Vault bootstrapping is no longer required, so we can eliminate even more janky shell scripting
* Our E2E exercises HCP, which is important to us as an organization
* With the reduction in configurability, we can simplify the Terraform configuration and drop the complicated `provision.sh`/`provision.ps1` scripts we were using previously. We can template Nomad configuration files and upload them with the `file` provisioner.
* Packer builds for Linux and Windows become much simpler.
tl;dr way less janky shell scripting!
This PR adds a set of tests to the Consul test suite for testing
Nomad OSS's behavior around setting Consul Namespace on groups,
which is to ignore the setting (as Consul Namespaces are currently
an Enterprise feature).
Tests are generally a reduced facsimile of existing tests, modified
to check behavior of when group.consul.namespace is set and not set.
Verification is oriented around what happens in Consul; the in-depth
functional correctness of these features is left to the original tests.
Nomad ENT will get its own version of these tests in `namespaces_ent.go`.
