feat(auth): add support for managing custom headers in auth files

Closes #2457

internal/store/gitstore.go

@@ -446,6 +446,7 @@ func (s *GitTokenStore) readAuthFile(path, baseDir string) (*cliproxyauth.Auth,
 	if email, ok := metadata["email"].(string); ok && email != "" {
 		auth.Attributes["email"] = email
 	}
+	cliproxyauth.ApplyCustomHeadersFromMetadata(auth)
 	return auth, nil
 }
 

internal/store/objectstore.go

@@ -595,6 +595,7 @@ func (s *ObjectTokenStore) readAuthFile(path, baseDir string) (*cliproxyauth.Aut
 		LastRefreshedAt:  time.Time{},
 		NextRefreshAfter: time.Time{},
 	}
+	cliproxyauth.ApplyCustomHeadersFromMetadata(auth)
 	return auth, nil
 }
 

internal/store/postgresstore.go

@@ -310,6 +310,7 @@ func (s *PostgresStore) List(ctx context.Context) ([]*cliproxyauth.Auth, error)
 			LastRefreshedAt:  time.Time{},
 			NextRefreshAfter: time.Time{},
 		}
+		cliproxyauth.ApplyCustomHeadersFromMetadata(auth)
 		auths = append(auths, auth)
 	}
 	if err = rows.Err(); err != nil {