Create a public Postman collection

[aoudiamoncef]

In order to improve Massa JSONRPC API consummation, we could create and share a public Postman collection. It'll complete OpenRPC Playground which gives us an interactive documentation.

Added methods:

• [ ] execute_read_only_call
• [ ] execute_read_only_bytecode
• [x] get_addresses
• [x] get_block
• [x] get_blockclique_block_by_slot
• [x] get_cliques
• [x] get_datastore_entries
• [x] get_endorsements
• [ ] get_filtered_sc_output_event
• [x] get_graph_interval
• [x] get_operations
• [x] get_stakers
• [x] get_status
• [x] get_staking_addresses
• [ ] send_operations
• [x] add_staking_secret_keys
• [x] node_ban_by_id
• [x] node_ban_by_ip
• [x] node_remove_from_whitelist
• [x] node_sign_message
• [x] node_unban_by_id
• [x] node_unban_by_ip
• [x] node_whitelist
• [x] remove_staking_addresses
• [x] stop_node