feat: add commands for managing organizations and users

Introduce `AddUserToOrganization`, `RemoveAPIKey`, and 
`RemoveOrganization` commands to enhance organization 
management. Implement validation for user addition and 
API key removal. Update GraphQL schema to support new 
mutations and add caching for the new events, ensuring 
that organizations and their relationships are accurately 
represented in the cache.

sdlmerge/sdlmerge.go

@@ -1,6 +1,7 @@
 package sdlmerge
 
 import (
+	"bytes"
 	"fmt"
 	"strings"
 
@@ -61,12 +62,13 @@ func MergeSDLs(SDLs ...string) (string, error) {
 		return "", fmt.Errorf("merge ast: %w", err)
 	}
 
-	out, err := astprinter.PrintString(&doc)
-	if err != nil {
+	// Format with indentation for better readability
+	buf := &bytes.Buffer{}
+	if err := astprinter.PrintIndent(&doc, []byte("  "), buf); err != nil {
 		return "", fmt.Errorf("stringify schema: %w", err)
 	}
 
-	return out, nil
+	return buf.String(), nil
 }
 
 func validateSubgraphs(subgraphs []string) error {