feat(managed-secrets): add centrally managed secrets with GITOPS_ prefix pushed to multiple targets

Introduce managed secrets owned by GitOps that can be defined once and
pushed to any combination of projects/groups across connections. Values
are stored in OS keychain, secrets appear on targets as GITOPS_{key}.

ts_interfaces/data/index.ts

@@ -6,3 +6,4 @@ export * from './secret.ts';
 export * from './pipeline.ts';
 export * from './actionlog.ts';
 export * from './sync.ts';
+export * from './managedsecret.ts';