Support new flags in actions

[ramya18101]

🔧 Changes

Adds schema discovery and JSON input to auth0 actions create / auth0 actions update, driven by the Auth0 Management API OpenAPI schema. Payloads are validated locally before any API call — making the commands easy to drive from AI agents and automation.

New flags:

• --schema — Print the request payload schema and exit (--json for machine-readable output).
• --data — Supply the full payload as JSON: inline, a file (@action.json), or stdin (--data - or piped). Mutually exclusive with granular input flags .

📚 References

• OpenAPI spec: https://auth0.com/docs/oas/management/v2/management-api-oas.json

🔬 Testing

• Unit tests: internal/openapi/*_test.go, internal/cli/data_json_test.go (schema load/resolve, validation, error enhancement, --data parsing).
• Manual: --schema (text + --json); --data inline / @file / stdin; invalid payloads report all errors pre-call; 400 includes expected schema.

📝 Checklist

• All new/changed/fixed functionality is covered by tests (or N/A)
• I have added documentation for all new/changed functionality (or N/A)