Add create, list, lookup functions for plugin based host catalogs (#1515)

Create the repository for plugin host catalogs.  A large TODO is left in the code to interface with the plugin system once ready.

internal/host/plugin/immutable_fields_test.go

@@ -24,7 +24,7 @@ func TestPluginCatalog_ImmutableFields(t *testing.T) {
 	o, prj := iam.TestScopes(t, iam.TestRepo(t, conn, wrapper))
 	plg := host.TestPlugin(t, conn, "test", "prefix")
 	plg2 := host.TestPlugin(t, conn, "test2", "prefix2")
-	new := TestCatalog(t, conn, plg.GetPublicId(), prj.PublicId)
+	new := TestCatalog(t, conn, prj.PublicId, plg.GetPublicId())
 
 	tests := []struct {
 		name      string
@@ -98,7 +98,7 @@ func TestPluginSet_ImmutableFields(t *testing.T) {
 	ts := timestamp.Timestamp{Timestamp: &timestamppb.Timestamp{Seconds: 0, Nanos: 0}}
 	_, prj := iam.TestScopes(t, iam.TestRepo(t, conn, wrapper))
 	plg := host.TestPlugin(t, conn, "test", "prefix")
-	cat := TestCatalog(t, conn, plg.GetPublicId(), prj.PublicId)
+	cat := TestCatalog(t, conn, prj.PublicId, plg.GetPublicId())
 	new := TestSet(t, conn, cat.GetPublicId())
 
 	tests := []struct {