Add support for namespaces (Consul Enterprise)

[vlatkoboshkoski-rldatix]

This is implementation of the namespace feature in Consul that is available in the Enterprise version only.
https://www.consul.io/api-docs/txn#namespace

Discussed here: #27

[vlatkoboshkoski-rldatix]

Do you need any additional info from me? Probably you can not test the enterprise features.

[paulo-ferraz-oliveira]

Hi, @vlatkoboshkoski-allocate.

This pull request has conflicting files, so a rebase is probably in order.

Also, would it be possible for you to add some tests, for future non-regression?

Thanks.

[vlatkoboshkoski-rldatix]

I am not sure about the tests, you will need Terraform Enterprise account to test it

[vlatkoboshkoski-rldatix]

Any updates? @paulo-ferraz-oliveira

[paulo-ferraz-oliveira]

Only saw this now, sorry about that.

I'm not saying I should write or do tests 😄

What I mentioned is we'd like you to add some tests (maybe mock something) so there's no future regressions against your changes.

Thanks.