Feature Request: Include Analytics-mapped XDM fields in Processing Rules

### Expected Behaviour
To be able to set events/evars/props using Processing Rules based on any XDM field.

### Actual Behaviour
XDM Fields that are automatically mapped to Analytics (like web.webPageDetails or web.webInteraction) are unavailable in Processing Rules. I was hoping it meant that they just don't lazy-load, but it seems like they cannot be manually entered either.

### Reproduce Scenario (including but not limited to)

#### Steps to Reproduce

#### Platform and Version

#### Sample Code that illustrates the problem
A very important one is **a.x.web.webinteraction.name**. I'd love to be able to use Processing Rules to conditionally set an event based on the value of this field. For example: if the value is set to "Click to Call" then set event2. Unfortunately, this isn't possible. So the solution is to edit the schema and push this information to a new field via custom mixin, and use that only for Processing Rules.

There are plenty of reasons to use the other auto-mapped XDM fields in processing rules too though, not just webinteraction.name.

#### Logs taken while reproducing problem