Add ability to discover steps from other plugins #243
Description
Similar to https://github.com/catalyst/moodle-tool_dynamic_cohorts?tab=readme-ov-file#technical-details we want other plugins to be able to implement steps and don't commit the code to tool_trigger code base.
In some cases there are some really specific steps that would never land to the core of the plugin so currently contributors have to fork the plugin as it's not flexible enough. We would like to have this flexibility.