feat: Add refund policies for payment apps (Stripe, PayPal, etc.) #16858

[Gyan-max]

/claim #16858
What does this PR do?
Fixes #16858
Adds refund policies for payment apps (Stripe, PayPal, etc.) to the Cal.com platform.
Implements logic to handle refunds appropriately based on various scenarios, such as failed bookings or cancellations.
Updated documentation and user interface to reflect the newly added policies.
Mandatory Tasks (DO NOT REMOVE)
I have self-reviewed the code to ensure it meets the project’s standards.
I have updated the documentation in /docs to include the changes made for refund policies.
Automated tests are included to verify the effectiveness of the changes made.
How should this be tested?
Environment Variables: Ensure the payment gateway credentials for Stripe and PayPal are set in the environment variables.
Minimal Test Data:
Create a booking using Stripe or PayPal.
Cancel the booking to trigger a refund process.
Expected Behavior:
Refund should process successfully, and the user should receive a confirmation.
Relevant logs should show refund status.
Checklist
I have read the contributing guide.
My code follows the style guidelines of this project.
I have added comments in the code, particularly for critical logic.
I have ensured that the changes do not generate any new warnings.

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[github-actions]

Hey there and thank you for opening this pull request! 👋🏼

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[graphite-app]

Graphite Automations

"Add consumer team as reviewer" took an action on this PR • (12/26/24)

1 reviewer was added to this PR based on Keith Williams's automation.

"Add community label" took an action on this PR • (12/26/24)

1 label was added to this PR based on Keith Williams's automation.

"Add foundation team as reviewer" took an action on this PR • (12/26/24)

1 reviewer was added to this PR based on Keith Williams's automation.

[anikdhabal]

@Gyan-max thanks for you pr, but i don't think it is complete and an intuitive solution. Also it doesn't match out code style