Create Sub-accounts screen should have default currency same as parent, not app-default currency

[prakhargahlot]

Create Sub-accounts screen should have default currency same as parent, not app-default currency. This makes it convenient to create a parallel currency tree by not having to select the parent's currency again and again.

Steps to reproduce the behaviour

1. Create an account of a currency (say GBP) which is different from app default currency (say USD).
2. Tap on "+" to create a sub-account.

Expected behaviour

The currency selected by default should be GBP

Actual behaviour

The currency selected by default is USD

Software specifications

• GnuCash Android version: 2.4.0
• System Android version: 9
• Device type: OnePlus 6T