Add phone number field when channel is phone on Payment Request doctype (copy #44949)

[mergify]

This PR introduces enhancements to the Payment Request functionality in ERPNext, specifically targeted at phone-based payment channels like Mpesa STK Push. The feature allows the system to capture and process a phone number during payment requests, ensuring seamless integration with payment gateways. Fixing Issue #44945

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Changes Implemented:

1. Added Phone Number Field:

   • Introduced a new Phone Number field in the Payment Request doctype.
   • The field is conditionally visible and required when the selected payment channel is Phone.

2. External Argument Handling:

   • Enhanced the system to accept a Phone Number via external arguments (e.g., from Webshop or POS).

3. Integration with request_for_payment:

   • Included the Phone Number in the arguments passed to the request_for_payment method.
   • Ensured compatibility with the Mpesa Settings doctype, where the STK push process is initiated.

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Key Benefits:

1. Streamlined Payment Workflow:
   • Automatically captures and utilizes the payer’s phone number, removing manual intervention.
2. Improved Integration:
   • Seamlessly supports Webshop and POS scenarios where phone numbers are essential for payment processing.
3. Enhanced User Experience:
   • Enables real-time STK push payments, particularly useful for Mpesa and similar phone-based payment systems.

Should be merged to both versions 15+ going forward

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This is an automatic copy of pull request #44949 done by [Mergify](https://mergify.com).

[mergify]

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	both modified:   erpnext/accounts/doctype/payment_request/payment_request.json
	both modified:   erpnext/accounts/doctype/payment_request/payment_request.py

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