Following the introduction of a service to define blockable actions in T279556, extensions may want to be able to define blockable actions. (For example T242785: Allow a user to be blocked from sending thanks.)
We can allow this by introducing a hook in the service's getAllBlockActions method.
An example of how the hook might be implemented can be found in https://gerrit.wikimedia.org/r/c/mediawiki/core/+/615837