Custom SMTP Settings (#561)

* Custom SMTP Settings

* Fix lint

* Custom SMTP add in Pricing plan

* Allow reset email settings

* improve custom SMTP using seprate abstract class

* test case for custom SMTP

* fix test case

* UI improvement

* add CASHIER_KEY in phpunit for testcase

* Attempt to fix tests

* Run pint and attempt to fix cache tests

* Fix user management tests

* Fix code linters

* Merged main & fix linting

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Co-authored-by: Julien Nahum <julien@nahum.net>

client/components/pages/pricing/PricingTable.vue

@@ -212,7 +212,8 @@ export default {
       "Larger file uploads (50mb)",
       "Remove OpnForm branding",
       "Priority support",
-      "Form Analytics"
+      "Form Analytics",
+      "Custom sender email (SMTP)"
     ],
   }),