Introduce predicate caching as an opt-in setting

[seadowg]

Work towards #5410
Blocked by getodk/javarosa#713

For the moment, predicate caching is off by default and can be enabled from "Experimental" settings.

What has been done to verify that this works as intended?

Verified manually.

Why is this the best possible solution? Were any other approaches considered?

Not a lot to discuss here. I introduced a new FormEntryControllerFactory component to allow us to isolate building/configuring a FormEntryController. I expect we'll end up with even more configuration down the line as part of this work, so that should hopefully become an important foundation.

How does this change affect users? Describe intentional changes to behavior and behavior that could have accidentally been affected by code changes. In other words, what are the regression risks?

The only change in behaviour we should see is that switching between screens during form entry should now be faster for forms like the example in getodk/javarosa#689. We'll want to discuss some strategies for trying to break the caching introduced here, but for now our plan is to merge without QA to get as many people testing it as possible. As the feature is a beta only opt-in the risk is very limited and we shouldn't see this breaking anything for real projects.

Before submitting this PR, please make sure you have:

• run ./gradlew checkAll and confirmed all checks still pass OR confirm CircleCI build passes and run ./gradlew connectedDebugAndroidTest locally.
• verified that any code or assets from external sources are properly credited in comments and/or in the about file.
• verified that any new UI elements use theme colors. UI Components Style guidelines