create resend.com plugin template

[ryomahan]

• [x] I hereby declare this contribution to be licenced under the MIT license

@atompie There is a resend.com plugin demo.

You can test with the plugin named Resend: Send Email, and this plugin is implemented for send email API.

Could you please review this code to see if there are any issues with the coding logic.

[ryomahan]

Please also let me know if there are no issues and I will continue to complete the remaining features of this plugin.