Add the possibility of "resend mailing"

This dev add the possibility to use the extension "resendmailing"

• https://lab.civicrm.org/extensions/resendmailing

The develop add a selector in the "Step" configuration, processor (by default the option is "mailing"), and if the extension resendmailing is enabled is added a option to the selector "Resend Mailing" (to avoid the dependencie)

When a step is executed for the first time, if the processor is configured as "Resend Mailing" the configuration is locked, and the step processor type and mailing cannot be changed. Displaying a message with a warning

Pd: Added this new selector "Processor" to add later the "sms processor".

Refs

• Related previous MR: !32 (closed)
• New MR: !33 (closed)