feat(order_object): add native support for CONDITIONAL orders

[deividuvi]

Summary

This PR adds first-class support for CONDITIONAL orders to the Python SDK by extending order_object.py.

The goal is to make conditional / stop orders a native SDK feature instead of relying on TPSL workarounds.

Changes

• Introduced native OrderType.CONDITIONAL support
• Added OrderConditionalTriggerParam for conditional trigger configuration
• Updated create_order_object() to:
  • Validate conditional-specific parameters
  • Correctly serialize conditional triggers into the order payload
• Preserved full backward compatibility with existing order types (LIMIT, MARKET, TPSL)

Motivation

Conditional orders are the primary mechanism used by the Extended exchange UI for stop-loss and protective exits.
Without native support, SDK users must rely on TPSL parent orders, which introduces complexity and edge cases.

This change enables:

• Clean reduce-only stop-loss orders
• Break-even protection
• Trailing stop engines built directly on conditional orders

Notes

• No breaking changes
• No changes to public APIs outside order_object.py
• Tested in live trading conditions on Extended mainnet

[deividuvi]

Context / Motivation

In several trading flows (e.g. stop-loss, break-even, trailing exits), orders need to be created after an initial position is already open.

The current implementation in order_object.py hard-codes OrderType.LIMIT when instantiating NewOrderModel, which prevents creating OrderType.CONDITIONAL orders through the same path — even though the exchange natively supports them.

What this change does

This patch removes the hard-coded order type and allows NewOrderModel to accept and propagate any order type supported by the exchange (including CONDITIONAL), without altering existing behavior for limit/market orders.

Why it helps

This makes the SDK compatible with a broader class of strategies (e.g. post-entry SLs, trailing stops, risk-management automation) while remaining backward-compatible with existing usage.

Here you can see the sample code of the original file with the hardcode limitation:
order = NewOrderModel(
id=order_id,
market=market.name,
type=OrderType.LIMIT,
side=side,
qty=settlement_data.synthetic_amount_human.value,
price=price,
post_only=post_only,
time_in_force=time_in_force,
expiry_epoch_millis=to_epoch_millis(expire_time),
fee=fee_rate,
self_trade_protection_level=self_trade_protection_level,
nonce=Decimal(nonce),
cancel_id=previous_order_external_id,
settlement=settlement_data.settlement,
tp_sl_type=tp_sl_type,
take_profit=tp_trigger_model,
stop_loss=sl_trigger_model,
debugging_amounts=settlement_data.debugging_amounts,
builderFee=builder_fee,
builderId=builder_id,
reduce_only=reduce_only,
)