Add a skip condition to all tests slower than 100ms.
This change was made using `gotestsum tool slowest` with data from the
last 3 CI runs of master.
See https://github.com/gotestyourself/gotestsum#finding-and-skipping-slow-tests
With this change:
```
$ time go test -count=1 -short ./agent
ok github.com/hashicorp/consul/agent 0.743s
real 0m4.791s
$ time go test -count=1 -short ./agent/consul
ok github.com/hashicorp/consul/agent/consul 4.229s
real 0m8.769s
```
Also update the Docs and fixup the HTTP API to return proper errors when someone attempts to use Namespaces with an OSS agent.
Add Namespace HTTP API docs
Make all API endpoints disallow unknown fields
Roles are named and can express the same bundle of permissions that can
currently be assigned to a Token (lists of Policies and Service
Identities). The difference with a Role is that it not itself a bearer
token, but just another entity that can be tied to a Token.
This lets an operator potentially curate a set of smaller reusable
Policies and compose them together into reusable Roles, rather than
always exploding that same list of Policies on any Token that needs
similar permissions.
This also refactors the acl replication code to be semi-generic to avoid
3x copypasta.
