Currently, we’re using scalar values to trace paths. The problem with
that approach is that we can’t create a reliable hierarchy with them, as
we can’t know for sure when a path is the same for different rules. By
using an object, we can easily compare and create a parent-child
relationship with it.
While making these changes, I deemed it necessary to also create objects
to handle Name and Id, which makes the code simpler and more robust. By
having Name and Path, we can create specific stringifiers that allow us
to customise how we render those values.
I didn’t manage to make those changes atomically, which is why this
commit makes so many changes. I found myself moving back and forth, and
making all those changes at once was the best solution I found.
Because of how the validation engine works, there's no reason to keep
adding templates to each rule. Instead, creating a single rule that
handles templating rules will simplify the library greatly and shrink
the `Rule` interface.
Personally, I think this API is much more straightforward than the
`setTemplate()` method, as it's way more explicit which rule is being
templated.
