CloudMigrations: Add instance metadata to auth token (#85381)

* update how tokens are passed around

* rename structs

pkg/services/cloudmigration/cloudmigrationimpl/store.go

@@ -8,5 +8,6 @@ import (
 
 type store interface {
 	MigrateDatasources(context.Context, *cloudmigration.MigrateDatasourcesRequest) (*cloudmigration.MigrateDatasourcesResponse, error)
+	CreateMigration(ctx context.Context, token cloudmigration.Base64EncodedTokenPayload) error
 	GetAllCloudMigrations(ctx context.Context) ([]*cloudmigration.CloudMigration, error)
 }