Create fallback symbols

[Vasile-Peste]

Symbols may not be equal across all trading platforms, for example the Frankfurt 40 Index is represented as DAX40, DE40 or just GER40 depending on the trading platform.

This means that switching trading account could result in potential compatibility issues and the mission of Mida is to enforce platform-neutrality.

A potential solution would be adding the possibility to define fallback symbols for every operation that requires a symbol. For example

const order = await myAccount.placeOrder({
    symbol: "DAX40|GER40|DE40`,
    // ...
});