Improve JSON output

[thewhaleking]

JSON output exists in all commands, but is inconsistent. It should use well-defined schemas.

[taoleeh]

JSON outputs nothing with btcli subnets list --json-out.

Tried with alacritty and kitty, same empty output.

Python version: 3.12.12
BTCLI version: 9.17.0
Network or Chain which was being used to interact with Subtensor: finney