Add the option 'Every time cron runs' for the time frecuency

Problem/Motivation

The 'Every time cron runs' option that is present in the 7.x module version is missing in the 8.x version.

Proposed resolution

Add the 'Every time cron runs' option for the time frecuency.

Remaining tasks

None.

User interface changes

None.

API changes

None.

Data model changes

None.