Retention - Provide a way to make event-based rules scalable

As a records manager, I can create event-based rules that can incorporate conditions to work at scale.

e.g.:

• When closing an account, I can provide the account number
• When an employee leaves the company, I can provide the employee number or employee id

AC:

• I can define an expression in an event-based rule
• The input of the event can be used in the expression
  • e.g., document.properties.employeeID == myinput where myinput is the input of the event
• When an expression is defined, it is evaluated against the input sent while firing the event
  • e.g. when firing an event Retention.employeeOffboarding with input "toto123", we start retention on any document where employeeID is "toto123"

NOTES
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The current way to create an event-based retention rule requires providing a hardcoded value. By using this option, a rule must be created for every potential value (e.g., create a rule for every account that can be closed or employee that is in the company). This is not scalable.

Our backend already has a property that could be leveraged to provide an EL expression:

retention_def:expression

However the event listener we use when we fire a retention event does not leverage it:
https://github.com/nuxeo/nuxeo-retention/blob/15479203e27f22bc6efb98dfb285d855e03e9e1c/nuxeo-retention/src/main/java/org/nuxeo/retention/listeners/RetentionBusinessEventListener.java#L68