agent: return req error if prometheus metrics are disabled.

The expose handler hook must handle if the submitted job is invalid. Without this validation, the rpc handler panics on invalid input.
Co-authored-by: Tim Gross <tgross@hashicorp.com>

Co-authored-by: Tim Gross <tgross@hashicorp.com>

Includes swapping the previously documented `-login` flag for `-authenticate`
to align better with Waypoint.

Endpoints for requesting and exchanging one-time tokens via the HTTP
API. Includes documentation updates.

RPC endpoints for the user-driven APIs (`UpsertOneTimeToken` and
`ExchangeOneTimeToken`) and token expiration (`ExpireOneTimeTokens`).
Includes adding expiration to the periodic core GC job.

The `OneTimeToken` struct is to support the `nomad ui -login` command. This
changeset adds the struct to the Nomad state store.

UI: Line Chart new primitives and tooltip refactor

As @backspace pointed out, we're processing a bunch of other stuff
anyway, so might as well process the active state there too where it's
more likely to be expected.

Update to Golang 1.16

Golang 1.16 added better support for installing tools, without updating
go.mod files: https://blog.golang.org/go116-module-changes#TOC_4. .

Maintaining patch versions is burdensome, and historical info is already
present in git history.

If the user has disabled Prometheus metrics and a request is
sent to the metrics endpoint requesting Prometheus formatted
metrics, then the request should fail.

Some charts intentionally don't yield a tooltip to show the possibility.

It is now required to use the one yielded by the :after named block.

Under a new Charts/Primitives section in Storybook

This also required re-ordering the SCSS imports since this depends on
colors introduced by bulma.

Expect this to be set on the visual yielded components directly

When a @dataProp is provided, the LineChart component assumes data is an
array of data series. It will map by the data prop and flatten to
compute the domains of the data.