Add option to group properties for payment providers

[bjarnef]

Is your feature request related to a problem? Please describe.
At the moment custom properties is listed in a long list, but possible to set a sort order for each of them. Furthermore there is a IsAdvanced property, where properties having this set to true is collapsed. Instead it would be great to be able to group properties.

Describe the solution you'd like
A way to group payment provider properties, e.g. via attributes. If nothing is specified it could be grouped in a "General" group or similar. E.g. you might want to create a group for "Billing" and "Shipping" since some payment providers support this. Maybe you also want to move secret, api keys, webhook settings etc. to a group. It would be great both to be able to sort properties in the group and sort each group.