Placeholder Plugin Providers for Repos and added testPlugin struct (#1532)

* Create minimalistic plugin map and test plugin.

* Pass secrets and attributes to the plugin when creating catalogs or sets.  Add tests for CreateSet and CreateCatalog repo methods.

* make fmt and extract out getPrivateCatalog and getCatalog helper methods.

* Exporting TestPluginServer so it can be used in the handlers.

* Keep separate persisted data from host catalogs lookups which facilitate passing it onto the plugins.

* Add TODO to merge get Catalog and get Persisted data.

* Adding tests for unimplemented being returned by the plugin.

* Use GetFields() instead of AsMap() to confirm attributes should be populated. Make clone consistent between catalog and sets.

Co-authored-by: Jeff Mitchell <jeffrey.mitchell@gmail.com>

internal/host/plugin/testing_test.go

@@ -9,6 +9,7 @@ import (
 	"github.com/hashicorp/boundary/internal/iam"
 	"github.com/hashicorp/boundary/internal/kms"
 	"github.com/hashicorp/boundary/internal/plugin/host"
+	plgpb "github.com/hashicorp/boundary/sdk/pbs/plugin"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -46,7 +47,7 @@ func Test_TestSet(t *testing.T) {
 	assert.NotEmpty(plg.GetPublicId())
 
 	c := TestCatalog(t, conn, prj.GetPublicId(), plg.GetPublicId())
-	set := TestSet(t, conn, kmsCache, c, WithName("foo"), WithDescription("bar"))
+	set := TestSet(t, conn, kmsCache, c, map[string]plgpb.HostPluginServiceServer{plg.GetPublicId(): &TestPluginServer{}}, WithName("foo"), WithDescription("bar"))
 	assert.NotEmpty(set.GetPublicId())
 	assert.True(strings.HasPrefix(set.GetPublicId(), fmt.Sprintf("%s_%s", HostSetPrefix, "prefix")))
 	assert.Equal("foo", set.GetName())