Adjust 'stamp calculator' to be a 'tx simulator'

[Endogen]

Description

This will give us the possibility to simulate transactions by only supplying the encoded payload dict. No signing needed. Since this is more than just a stamp calculator, I renamed it to 'simulator'.

This is tested and working. I've also reworked xian-py to reflect these adjustments and explicitly added a method to simulate transactions: xian-network/xian-py#2

To have it really clean and making sense, I've added a simulate_tx endpoint to query.py that should over time replace the calculate_stamps endpoint.

Our Chrome wallet and possibly JS tools would need to be adjusted

Example script

from xian_py.wallet import Wallet
from xian_py.xian import Xian
from xian_py.transaction import (
    get_nonce,
    simulate_tx
)

node_url = 'http://127.0.0.1:26657'
wallet = Wallet('cd6cc45ffe7cebf09c6c6025575d50bb42c6c70c07e1dbc5150aaadc98705c2b')

xian = Xian(
    node_url,
    wallet=wallet
)

payload = {
    "contract": "currency",
    "function": "transfer",
    "kwargs":
    {
        "to": "8bf21c7dc3a4ff32996bf56a665e1efe3c9261cc95bbf82552c328585c863829",
        "amount": 1.11,
    },
    "nonce": get_nonce(node_url, wallet.public_key),
    "stamps": 0,
    "chain_id": xian.get_chain_id(),
    "sender": wallet.public_key
}
print(f'payload: {payload}')

simulated_tx = simulate_tx(node_url, payload)
print(f'simulated tx: {simulated_tx}')

Endpoint INPUT

{
    'contract': 'currency',
    'function': 'transfer',
    'kwargs':
    {
        'to': '8bf21c7dc3a4ff32996bf56a665e1efe3c9261cc95bbf82552c328585c863829',
        'amount': 1.11
    },
    'nonce': 2,
    'stamps': 0,
    'chain_id': 'unique-chain-id-goes-here',
    'sender': 'ee06a34cf08bf72ce592d26d36b90c79daba2829ba9634992d034318160d49f9'
}

Endpoint OUTPUT

{
    'payload':
    {
        'chain_id': 'unique-chain-id-goes-here',
        'contract': 'currency',
        'function': 'transfer',
        'kwargs':
        {
            'amount': 1.11,
            'to': '8bf21c7dc3a4ff32996bf56a665e1efe3c9261cc95bbf82552c328585c863829'
        },
        'nonce': 2,
        'sender': 'ee06a34cf08bf72ce592d26d36b90c79daba2829ba9634992d034318160d49f9',
        'stamps': 0
    },
    'result': 'None',
    'stamps_used': 10,
    'state': [
    {
        'key': 'currency.balances:ee06a34cf08bf72ce592d26d36b90c79daba2829ba9634992d034318160d49f9',
        'value': '61111008.32100000'
    },
    {
        'key': 'currency.balances:8bf21c7dc3a4ff32996bf56a665e1efe3c9261cc95bbf82552c328585c863829',
        'value': '2.22'
    }],
    'status': 0
}

Type of change

• New feature (non-breaking change which adds functionality)

Checklist

• I have performed a self-review of my own code
• I have tested this change in my development environment.
• I have added tests to prove that this change works
• All existing tests pass after this change
• I have added / updated documentation related to this change

[Endogen]

@duelingbenjos The only thing i see that we should think more about: If the provided payload doesn't include everything needed, it will not tell you.

[duelingbenjos]

looks good, we must keep the old endpoint intact though.