feat: Reexport some uniffi types for type sharing in-between generated Python packages

[tmathern]

Reexport some uniffi types for type sharing in-between generated Python packages.

Caveat: Python packages sharing the types need exact match of maturin+uniffi version.

[gpeacock]

I updated my makefile to build rust and run pytest like this:

release:
	cargo build --release

build: release
	rm -rf c2pa/c2pa
	python3 -m pip uninstall -y maturin
	python3 -m pip uninstall -y uniffi
	python3 -m pip install -r requirements.txt
	maturin develop

test: build
	python3 -m pytest

[gpeacock]

looks good, though you may want to update the makefile to build rust and run unit tests (as in the example I posted)