A mostly cosemetic change; The fields 'workspace' and 'prefix' don't
really describe well what they are from a caller, so change these to use
a workspaceMapping struct to convey they are for implementing workspace
mapping strategies from CLI -> TFC
These changes include additions to fulfill the interface for the client
mock, plus moving all that logic (which needn't be duplicated across
both the remote and cloud packages) over to the cloud package under a
dedicated mock client file.
The cloud package intends to implement a new integration for
Terraform Cloud/Enterprise. The purpose of this integration is to better
support TFC users; it will shed some overly generic UX and architecture,
behavior changes that are otherwise backwards incompatible in the remote
backend, and technical debt - all of which are vestiges from before
Terraform Cloud existed.
This initial commit is largely a porting of the existing 'remote'
backend, which will serve as an underlying implementation detail and not
be a typical user-level backend. This is because to re-implement the
literal backend interface is orthogonal to the purpose of this
integration, and can always be migrated away from later.
As this backend is considered an implementation detail, it will not be
registered as a declarable backend. Within these changes it is, for easy
of initial development and a clean diff.