Fix: add fee to donation amount if any

[ravinderk]

Ticket GIVE-91
Resolves https://feedback.givewp.com/bug-reports/p/paypal-donations-ignores-fee-recovery-in-v3-forms
Slack Discussion https://lw.slack.com/archives/C02R3EB3SGM/p1699891955017429

Description

I found that we were not adding a fee to the donation amount when processing transactions with PayPal Donations. I updated the logic to add a fee to the donation amount if a fee exists.

Affects

This pull request affects one-time and subscription processing.

Testing Instructions

• The Donor should be able to process one time donation with or without fee.
• The Donor should be able to process one subscription donation with or without fee.
• The donation amount should match and correct in donation details and in the PayPal dashboard.

Pre-review Checklist

• Acceptance criteria satisfied and marked in related issue
• Relevant @unreleased tags included in DocBlocks
• Includes unit tests
• Reviewed by the designer (if follows a design)
• Self Review of code and UX completed

[glaubersilva]

@ravinderk Sorry for the late here. Looks good to me, ready for QA!

[rickalday]

Passed manual and automated QA tests.