798: incremental parameter for geotrace and geoshape

[lindsay-stevens]

Closes #798

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

Uses existing patterns for validation and error codes. Considered refactoring the geo parameters into a separate module but this PR is needed quickly. Other minor changes from the ticket:

• anticipating something like Accept standard true/false aliases for auto_send and auto_delete #767 the aliases of true are accepted (yes, true(), etc)
• an error is raised if the question is geoshape or geotrace, and the incremental parameter is there, but the value is not recognised. That seemed more helpful than ignoring the value since that'd be a likely scenario for a typo. Also an error is raised if incremental is specified for other question types that accept parameters, which is current behaviour. Otherwise it is ignored.

What are the regression risks?

Should be none since it's a new parameter.

Does this change require updates to documentation? If so, please file an issue here and include the link below.

Spec and xlsform.org

Before submitting this PR, please make sure you have:

• included test cases for core behavior and edge cases in tests
• run python -m unittest and verified all tests pass
• run ruff format pyxform tests and ruff check pyxform tests to lint code
• verified that any code or assets from external sources are properly credited in comments

[lognaturel]

Thanks so much! I took the liberty of templating in values since that seemed like the clear intent.