cloud: Use copy.DeepCopyValue instead of copystructure dependency

The mock implementations of the Terraform Cloud SDK types were previously
using the rather-heavy external dependency mitchellh/copystructure for
creating deep copies of the mock values.

This package doesn't need all of the customizability and generality of
that library, and so our smaller internal helper copy.DeepCopyValue is
sufficient.

internal/cloud/tfe_client_mock.go

@@ -19,8 +19,8 @@ import (
 	"time"
 
 	tfe "github.com/hashicorp/go-tfe"
-	"github.com/mitchellh/copystructure"
 
+	"github.com/hashicorp/terraform/internal/copy"
 	tfversion "github.com/hashicorp/terraform/version"
 )
 
@@ -1026,11 +1026,8 @@ func (m *MockProjects) List(ctx context.Context, organization string, options *t
 	pl := &tfe.ProjectList{}
 
 	for _, project := range m.projects {
-		pc, err := copystructure.Copy(project)
-		if err != nil {
-			panic(err)
-		}
-		pl.Items = append(pl.Items, pc.(*tfe.Project))
+		pc := copy.DeepCopyValue(project)
+		pl.Items = append(pl.Items, pc)
 	}
 
 	pl.Pagination = &tfe.Pagination{
@@ -1051,12 +1048,8 @@ func (m *MockProjects) Read(ctx context.Context, projectID string) (*tfe.Project
 	}
 
 	// we must return a copy for the client
-	pc, err := copystructure.Copy(p)
-	if err != nil {
-		panic(err)
-	}
-
-	return pc.(*tfe.Project), nil
+	pc := copy.DeepCopyValue(p)
+	return pc, nil
 }
 
 func (m *MockProjects) Update(ctx context.Context, projectID string, options tfe.ProjectUpdateOptions) (*tfe.Project, error) {
@@ -1068,12 +1061,8 @@ func (m *MockProjects) Update(ctx context.Context, projectID string, options tfe
 	p.Name = *options.Name
 
 	// we must return a copy for the client
-	pc, err := copystructure.Copy(p)
-	if err != nil {
-		panic(err)
-	}
-
-	return pc.(*tfe.Project), nil
+	pc := copy.DeepCopyValue(p)
+	return pc, nil
 }
 
 func (m *MockProjects) Delete(ctx context.Context, projectID string) error {
@@ -1241,11 +1230,8 @@ func (m *MockRuns) List(ctx context.Context, workspaceID string, options *tfe.Ru
 
 	rl := &tfe.RunList{}
 	for _, run := range m.workspaces[w.ID] {
-		rc, err := copystructure.Copy(run)
-		if err != nil {
-			panic(err)
-		}
-		rl.Items = append(rl.Items, rc.(*tfe.Run))
+		rc := copy.DeepCopyValue(run)
+		rl.Items = append(rl.Items, rc)
 	}
 
 	rl.Pagination = &tfe.Pagination{
@@ -1406,11 +1392,7 @@ func (m *MockRuns) ReadWithOptions(ctx context.Context, runID string, options *t
 	}
 
 	// we must return a copy for the client
-	rc, err := copystructure.Copy(r)
-	if err != nil {
-		panic(err)
-	}
-	r = rc.(*tfe.Run)
+	r = copy.DeepCopyValue(r)
 
 	// After copying, handle includes... or at least, any includes we're known to rely on.
 	if options != nil {