fix(lightning): use min0ConfTxFee only for orders with 0 client balance

[pwltr]

Description

BT only accepts turbo or 0-conf payment channels for orders with 0 client balance. The min-0conf-tx-fee is also sometimes excessive. We can use a lower fee for orders with a balance.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactoring (improving code without creating new functionality)

Tests

• Detox test
• Unit test
• No test