Feature Request: Make it so both Test and Live credentials are stored when switching between them

[KZeni]

Many of the payment gateways I've worked with (if not all at this point) have it so the switcher between Live/Production and Test/Sandbox actually keeps the credentials being used for both so it's a simple swap between each setup without needing to replace the credentials each time. Currently, this just has the one API token which doesn't swap out for test vs. live (requiring the credential to be replaced whenever changing the environment.)

I would love to see this implemented with this payment gateway setup to make testing this payment gateway much quick & easy to work with.

Thanks!