feat: add interactive api selection for resource server client creation

[patrickkang]

🔧 Changes

Improves the DX for creating resource server clients by adding an interactive API picker instead of requiring manual entry of the resource server identifier:

• When creating a resource server client without the --resource-server-identifier flag, users are now prompted to select from their existing APIs via an interactive picker
• Added validation to reject empty or whitespace-only identifiers when provided via flag
• Non-interactive usage with --resource-server-identifier flag continues to work as before

📚 References

• https://auth0team.atlassian.net/browse/AIDX-332

🔬 Testing

# prompts for selection
auth0 apps create --name "My Client" --type resource_server

# non-interactive(skips prompt)
auth0 apps create --name "My Client" --type resource_server --resource-server-identifier "https://api.example.com"

📝 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)

[ramya18101]

@patrickkang, Thanks for raising the PR..
We will review and get back to you soon!