HCP Vault Enterprise Image for s390x

[Joshua-Beha]

Is your feature request related to a problem? Please describe.
Currently, the Vault Enterprise container image is only avialable from Dockerhub for x86 and ARM. I am trying to deploy a containerized version of HCP Vault Enterprise on s390x and there does not appear to be a prebuilt image available.

Describe the solution you'd like
An addition to the build automation for also building the Vault enterprise container image for the s390x architecture.

Describe alternatives you've considered
It is possible to build the container image using the available HCP Vault Enterprise binary and the current Dockerfile in the root of this repository to create one's own image. This is less convenient than a publicly available image that has already been built.

Explain any additional use-cases
This would be helpful for both experimental deployments (IE compatibility with many of the tutorials where the container image is used) and production deployments with container orchestration tools like Red Hat OpenShift.

Additional context
NA