command: Apply tests with realistic mock providers
command: Apply tests with realistic mock providers

Now that we're actually verifying correct behavior of providers during
plan and apply, our mock providers need to behave like real providers,
properly propagating any configured values through the plan and into the
final state.

For most of these it was simpler to just switch over to using the newer
PlanResourceChangeFn mock interface, away from the legacy DiffFn approach,
because then we can just return the ProposedNewState verbatim because our
schema for these tests does not require any default values to be
populated.

ewbankkit/terraform,heimweh/terraform,hashicorp/terraform,mattray/terraform,rnaveiras/terraform,pdecat/terraform,ewbankkit/terraform,ewbankkit/terraform,ewbankkit/terraform,brandontosch/terraform,gechr/terraform,luis-silva/terraform,gechr/terraform,nlamirault/terraform,rnaveiras/terraform,rnaveiras/terraform,apparentlymart/terraform,luis-silva/terraform,pdecat/terraform,hashicorp/terraform,drebes/terraform,heimweh/terraform,mattray/terraform,mattray/terraform,drebes/terraform,drebes/terraform,pryorda/terraform,luis-silva/terraform,heimweh/terraform,hashicorp/terraform,heimweh/terraform,pdecat/terraform,apparentlymart/terraform,pryorda/terraform,apparentlymart/terraform,gechr/terraform,pradeepbhadani/terraform,pradeepbhadani/terraform,apparentlymart/terraform,tommynsong/terraform,heimweh/terraform,brandontosch/terraform,brandontosch/terraform,mattray/terraform,VladRassokhin/terraform,nlamirault/terraform,pryorda/terraform,VladRassokhin/terraform,brandontosch/terraform,nlamirault/terraform,VladRassokhin/terraform,VladRassokhin/terraform,tommynsong/terraform,tommynsong/terraform,drebes/terraform,apparentlymart/terraform,brandontosch/terraform,pdecat/terraform,pradeepbhadani/terraform,luis-silva/terraform