Implement metadata page in UI component

[niallthomson]

The UI should provide a page that outputs information about the environment the container is deployed in. This is useful for demonstrations where it is necessary to show aspects such as cross-AZ load balancing and many others.

This component should automatically determine where it is running by checking for things like the EC2 metadata endpoint, ECS metadata endpoint etc. It should likely be possible for multiple "contributors" to add to the metadata, for example one to provide Kubernetes metadata and another to provide EC2 metadata.

Examples of information that could be shown:

• Availability zone/region
• EC2 instance type
• ECS task family, revision
• Environment variables with a specific prefix, for example METADATA_CUSTOM_FIELD, which would allow use of Kubernetes downwards API

[awsjt]

I can take this.