Add "fee amount" to contribution processor

[kapn1966]

Is your feature request related to a problem? Please describe.
I am unable to add the fee amount (i.e. what the processor charges for a transaction) when using the contribution processor. There is an additional problem that the fee amount is not captured by the CF-Stripe plugin, but I assume that is a problem for the Caldera team, not for you.

Describe the solution you'd like
I'd like a field that allows the fee amount of a transaction (if known or returned from another processor) to be sent as part of the contribution record for more correct accounting.

Describe alternatives you've considered
There is no realistic alternative. In the absence of this feature, contribution records would need to be manually updated.

Additional context
Would like to see a field for "fee amount" on this settings page: