MAE-454: Add validations when creating membership payment plan

[erawat]

Overview

This PR adds two custom validations when creating a payment plan when using a price set.

Unit tests are also added to test validations.

Before

No custom validations implemented on version 5

After

Custom validations added to prevent user submit the form that will generate incorrect data.

The validations are:

• Validate if the membership period types are mixed of price field values. (rolling or fixed)
• Validate if fixed period membership type are selected with different period start days