[FEATURE] ✨ Add Complexity measure on FilterExpression

[candoumbe]

Is your feature request related to a problem? Please describe.
A complexity measure combine with IsEquivalentTo could help convert complex expressions to a less complex expression
For example, swapping two expressions that are equivalent
*[Mm]an and *Man|*man are equivalent but the first one is more complex than the latter because it requires several operations before being processable.

Describe the solution you'd like
Any FilterExpression would be able to give access to a Complexity measure that gives a sense of how cumbersome it is.
It will be a kind of cyclomatic complexity