Add trunkVersion and branchId support

[seadowg]

Closes #6245
Blocked by #6267

As well as adding support for forms to receive __trunkVersion and __branchId and keeping track of these values correctly, this also changes how we increment __version. Before, Collect would parse the baseVersion, increment it and then store the result. This meant that a form might manipulate the baseVersion in an unexpected way which would Collect would honour. After chatting with @lognaturel, we've decided that this was actually an incorrect implementation of the following line in the spec:

MUST increment the __version of its local entity representation by 1 when an update is successfully applied

Instead, we now increment our own representation of __version (Entity#version) and ignore the baseVersion in submissions.

I've also cleaned up how Collect treats forms that have both an update and a create action and added tests to define that behaviour.

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

Not a lot to discuss here! I'll put comments inline for anything that seems worth mentioning.

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?

This is mostly all additional, but there's a risk that changes to the way we increment version and to how we treat forms that have both an update and create action might alter how we expect Collect to behave. It'd be worth testing both of these out and checking we're happy with how everything works.

Before submitting this PR, please make sure you have:

• added or modified tests for any new or changed behavior
• run ./gradlew connectedAndroidTest (or ./gradlew testLab) and confirmed all checks still pass
• added a comment above any new strings describing it for translators
• added any new strings with date formatting to DateFormatsTest
• 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