[FRON-1465]: Check for the validity of the public and secret keys in the payment section when merchants adds them.

[aashishgurung]

1. Objective

Prevent merchants from entering invalid Omise Payment keys.

Jira Ticket: #1465 (https://omise.atlassian.net/browse/FRON-1465)

2. Description of change

Created a new plugin or interceptor ConfigSectionPaymentPlugin which holds logic to check the validity of the keys before saving it to the database. Did some refactoring on the Omise\Payment\Model\Config\Config.php.

3. Quality assurance

Run these command before testing:

php bin/magento cache:flush
php bin/magento setup:di:compile

Go the the payment configuration section and test the following cases.

Should be a success:

• Add accurate public and secret keys
• Add empty public and secret keys

Should fail

• Add either one of the keys accurate and let other be empty
• Add incorrect keys to any of them

🔧 Environments:

• Platform version: Magento CE 2.4.3
• Omise plugin version: Omise-Magento 2.23.2
• PHP version: 7.1.15

[kan98]

sorry I just saw PR is still in draft mode, can ignore my comments for now 🤦🏽